Israelectrochemistry

2019

Book of Abstracts

22.09.19-23.09.19

Scientific Program

09:00-9:45 Gathering and Registration

09:45-10:00 Welcome Greetings, Prof. Chaim Hames, Rector of the Ben-Gurion

University of the Negev

Morning Session (25 minutes talk + 5 minutes Q&A), Chairman: Ze'ev Porat

Morning Session I – Hall No. 3

10:00-10:30 Plenary Lecture: Probing Reactions at Electrochemical Interfaces

with X-ray Spectroscopies

Robert Weatherup, University of Manchester, United Kingdom

10:30-11:00 Invited Lecture: Evaluation of Ion-Transport in Composite

Polymer-In-Ceramic Electrolytes

Diana Golodnitsky, Tel-Aviv University, Israel

11:00-11:20 Coffee Break

Morning Session II – Hall No. 3

11:20-12:00 In Memoriam of the Late Professor Israel Rubinstein

Yuval Golan, Ze'ev Porat, Alexander Vaskevich, Bilha Rubinstein

12:00-12:30 Invited Lecture: Surface Engineering of High Energy Electrodes for

Lithium ion Batteries

Malachi Noked, Bar-Ilan University, Israel

12:30-13:00 Invited Lecture: Analysis of Electrochemical Impedance

Spectroscopy Measurements of Fuel Cells and Supercapacitors

Yoed Tsur, Technion - Israel Institute of Technology, Israel

13:00-14:30 Lunch, Posters Session, Vendor Exhibition

Afternoon Sessions (17 minutes talk + 3 minutes Q&A)

Afternoon Session I – Fuel Cells, Chairman: Lior Elbaz – Hall No. 3

14:30-14:55 Invited Lecture: Mass Transport in Electrocatalysis: The Role of

Nanostructure

David Eisenberg, Technion - Israel Institute of Technology, Israel

14:55-15:15 From "Nano To Nano": A New Approach for Electrochemical

Deposition

Daniel Mandler, The Hebrew University of Jerusalem, Israel

15:15-15:35 Electrocatalytic Reduction of CO2 and Oxidation of CO Catalyzed

by Polyoxometalates

Dima Azaiza-Dabbah, Weizmann Institute of Science, Israel

15:35-15:55 Electrocatalytic CO2 Reduction Exhibited by Confined CoTMPyP in

Electrodeposited Reduced Graphene Oxide

Yair Bochlin, Ben-Gurion University of the Negev, Israel

Afternoon Session II – Bio-electrochemistry, Chairman: Omer Yehezkeli – Hall No. 2

14:30-14:55 Invited Lecture: Utilizing Photosynthetic Organisms and Isolated

Complexes for Direct Solar Energy Conversion: Building Bio-

Photoelectrochemical Cells

Noam Adir, Technion - Israel Institute of Technology, Israel

14:55-15:15 Chitosan-Carbon Nanotube and Reduced Graphene Oxide -Modified

Microelectrode for Real-Time Detection of Antipsychotics

Rajendra P. Shukla, Ben-Gurion University of the Negev, Israel

15:15-15:35 Electron Transfer in Coordination-based Molecular Assemblies

Michal Lahav, Weizmann Institute of Science, Israel

15:35-15:55 Highly Efficient Flavin–Adenine Dinucleotide Glucose

Dehydrogenase Fused to A Minimal Cytochrome C Domain

Itay Algov, Ben-Gurion University of the Negev, Israel

15:55-16:10 Coffee break

Afternoon Session III – Storage, Chairman: Malachi Noked – Hall No. 3

16:10-16:40 Invited lecture: Hydrogen-Bromine Redox-Flow Batteries

David Zitoun, Bar Ilan University, Israel

16:40-17:00 3D-Printed Functional Materials for Electrochemical Energy

Storage

Heftsi Ragones, Tel-Aviv University, Israel

17:00-17:20 Metallo‐Organic Assemblies for Dual-Function Electrochromic

Supercapacitors

Ofir Eisenberg, Weizmann Institute of Science, Israel

17:20-17:40 Investigation of Novel N-Hetrocyclic Lithium Salt Dissolved in

Silane-Based Solvent as A Safe Electrolyte for High Power Lithium

Batteries

Yonatan Horowitz, Tel-Aviv University, Israel

17:40-18:00 Emerging Innovations in Material Characterizations for Energy

Storage and Conversion Using EQCM-D

Netanel Shpigel, Bar-Ilan University, Israel

Afternoon Session IV – Photo-electrochemistry, Chairman: Idan Hod – Hall No. 2

16:10-16:40 Invited lecture: Operando Characterization of Charge Extraction

Profiles in Semiconductor Photoelectrodes with Nanoscale Resolution

Gideon Segev, Tel Aviv University, Israel

16:40-17:00 Selective Charge Trapping and Release in Nanoscale Films

Yonatan Hamo, Weizmann Institute of Science, Israel

17:00-17:20 Electrochromic Metallo-Organic Films: Spray-Coating, On-Surface

Self Assembly, And Laminated Devices

Naveen Malik, Weizmann Institute of Science, Israel

17:20-17:40 Significance of H2O2 Photo-Oxidation in Water Splitting for Co-

Catalyst Design

Arik Yochelis, Ben-Gurion University of the Negev, Israel

17:40-18:00 Gold Nanoparticles as a Tool for Probing Corrosion Processes Alexander Vaskevich, Weizmann Institute of Science, Israel

18:00-18:30 Best Poster Award and Concluding Remarks

Oral Presentation Abstracts – by Order of Appearance

Probing Reactions at Electrochemical Interfaces with X-ray Spectroscopies Probing the chemical reactions occurring at electrochemical interfaces under realistic conditions is critical to selecting and designing improved materials for energy storage, chemical production, and corrosion prevention. Soft X-ray spectroscopies offer powerful element- and chemical-state-specific information with the required nm-scale interface sensitivity, but have traditionally required high vacuum conditions, impeding studies of liquid-phase environments.1 Here we introduce several membrane-based approaches developed in recent years in order to bridge this pressure gap, enabling operando x-ray photoelectron and absorption spectroscopy (XPS/XAS) of solid-liquid interfaces.2–5 These rely on reaction cells sealed with X-ray/electron-transparent membranes, that can sustain large pressure drops to the high-vacuum measurement chamber.2,3 Thin (<100 nm) silicon nitride membranes are commercially available and transparent to even soft X-rays, whilst graphene membranes have thicknesses below the inelastic mean free path of photoelectrons (typically < 2 nm) and yet remain highly impermeable to gases and liquids.4 We show how these membrane-based approaches can be applied to study the chemical evolution of solid-liquid interfaces under electrochemical control, including the oxidation/reduction of Ni electrodes,5 and the solid-electrolyte interphase formation on Li-ion battery anodes. The extension of soft x-ray spectroscopies to liquid environments offered by these approaches is expected to be valuable for the study of a wide range of interfacial reactions across the electrochemical sciences. References 1. Wu et al. Phys. Chem. Chem. Phys. 2015, 17, 30229. 2. Velasco-Velez et al. Angew. Chemie 2015, 54, 14554. 3. Weatherup et al. J. Phys. Chem. Lett. 2016, 7, 1622. 4. Weatherup et al. Top. Catal. 2018, 61, 2085. 5. Weatherup et al. J. Phys. Chem. B 2018, 122, 737.

EVALUATION OF ION-TRANSPORT IN COMPOSITE POLYMER-IN-CERAMIC ELECTROLYTES

D. Golodnitsky 1*, S. Menkin 1, M. Lifshitz 1, A. Haimovich 1, M. Goor 1, R. Blanga 1, S.G. Greenbaum 2, A. Goldbourt 1

1 School of Chemistry, Tel Aviv University, Tel Aviv, 69978, Israel

2 Department of Physics and Astronomy, Hunter College of the City University of New York, 10065, USA *e-mail: golod@tauex.tau.ac.il

Inorganic-ceramic- and organic-polymer-based solid electrolytes (SE) could revolutionize battery and supercapacitor technology because of their nontoxicity, stability during operation and enhanced safety. Of particular interest are electrolytes, which contain high concentrations of ion charge carriers with a minimum polymer concentration required for good flexibility and allowing the major ion-conduction path to go through the inorganic material. We have developed, and present here, novel thin-film polymer-in-ceramic composite electrolytes with high ion-conduction properties prepared by electrophoretic deposition. Commercial nanoparticles of LiAlO2, Li10SnP2S12, and Li1.5Al0.5Ge1.5(PO4)3 materials were used as ceramic matrices. Polyethyleneimine (PEI) and polyethylene oxide (PEO) were tested as binders and lithium-ion-conducting media. Our recently developed simplified Poisson-Boltzmann model reveals that the adsorption of PEI on the surface of ceramic particles increases zeta potential, repulsion forces between the particles and their deposition rate. We have succeeded in depositing films containing 5 to 40% PEO, which are homogeneous in composition and uniform in thickness. XRD and DSC tests showed that the crystallinity of the polymer confined in the pores of ceramics, is suppressed. This was expected to improve the ionic conductivity of composite electrolytes saturated with LiI salt. However, on the basis of AC-impedance and NMR data, we suggest that the high-ionic-conductivity (0.5 mS/cm) and low-activation-energy (2.3 kJ/mol) ion paths are brought about by the grain boundaries between the excess of LiI and inert LiAlO2 ceramic nanoparticles. Both confined-in-ceramic polymer electrolyte (PE) and ceramic LiAlO2 grains impede the total ion mobility. The fast ion transport in polymer-in-ceramic electrolytes composed of high-conductivity active Li10SnP2S12, goes through lithium-iodide-rich glass ceramics, and is restricted by slow ion transport via the imbedded polymer electrolyte. Unexpectedly, it was found that at 1:3 salt-to-polymer ratio, the contribution of grain-boundary conductivity in an inert-ceramics based composite electrolyte is stronger than that of bulk conductivity via active ceramic matrix. One of the possible reasons of the reduced relative contribution of the active ceramics to the total conductivity of polymer-in-ceramic electrolyte is that the ceramic powder was not densified. Acknowledgments The authors from Tel Aviv University wish to express their sincere thanks to Dr. Yuri Rosenberg, Dr. Larisa Burstein and Dr. Alex Gladkikh of the Wolfson Applied Materials Research Center for the XRD, XPS and TOF-SIMS characterizations of the samples. Partial support for this work was obtained from the Israeli Committee on Higher Education and the Israeli Prime Minister's office via the INREP project.

Surface Engineering of High Energy Electrodes for Lithium Ion Batteries.

Malachi Noked a a Chemistry department, Bar Ilan Institute for Nanotechnology and Advanced

Materials(BINA), Bar Ilan University, Israel

E-mail: Malachi.Noked@biu.ac.il

Powering most currently used portable devices, batteries ushered electronics into a new era of

mobile energy, directly supporting and influencing our daily lives. However, the ever-

increasing demand for energy storage devices with improved performances and is challenging

the scientific community to develop new chemistries and morphologies of electrode materials

(EM) to move beyond current technology toward electrochemical storage devices with higher

energy density, superior power performance and significantly extended stability.

Understanding of fundamental degradation mechanisms of EMs, and their mitigation

strategies, are challenged by constraints of the liquid electrolyte environment and the

complexity of electrode/electrolyte interphase formation, namely the solid electrolyte

interphase (SEI) layer which forms, grows, and changes (on the electrode interface) with battery

usage. Accordingly, the research community is increasingly seeking new pathways to

understand and control battery degradation, including new diagnostic and characterization

methods (e.g., synchrotron and in-situ studies) as well as mitigation strategies (e.g., electrode

surface treatments, electrolyte additives and artificial SEI layers).

In my talk I will demonstrate how surface modification of EMs, significantly suppress the

degradation of the battery components (e.g. electrodes, and electrolyte) and facilitates long-

term stability of the electrochemical device.

I will demonstrate how in our lab, we modify the surface of the EMs by either thin protection

layer applied on its interface (using atomic layer deposition- ALD), or by surface reduction of

high voltage cathode materials. I will farther show how we monitor In-Operando the

degradation of the electrode\electrolyte interface using online electrochemical mass

spectroscopy (OEMS), and will demonstrate the efficacy of our coating strategy in suppressing

the degradation pathway of the EMs.

Analysis of electrochemical impedance spectroscopy

measurements of fuel cells and supercapacitors

Yoed Tsur

Chemical Engineering Department, Grand Technion Energy Program, Technion,

Israel Institute of Technology

tsur@technion.ac.il

PEMFC already find their way to commercialization, especially in transportation. Still,

the issue of degradation has yet to be addressed [1]. The latter is true also for

supercapacitors. A primary tool in PEMFCs as well as SC operation study is

Electrochemical Impedance Spectroscopy (EIS) [2]. The common method for analysing

EIS measurements, the construction of an equivalent circuit, has several known

problems, such as the ambiguity of the model. Our group has developed a modified

genetic programming method, known as ISGP, [3] to solve the inverse problem of

finding the distribution function of relaxation times (DFRT) underlying an impedance

spectrum. It gives a functional form of the DFRT, which is very useful for further

analysis. Our program seeks DFRT that has the form of a sum of peaks, assuming the

Debye kernel. All the peaks are known functions; thus, the model is an analytic

functional form of the DFRT. ISGP avoids over-fitting and provides a consistent model

for different measurements over, e.g., degradation process. Here I will discuss the

application of ISGP to study those two important electrochemical systems: fuel cells

and supercapacitors [4].

[1] W. Schmittinger and A. Vahidi, “A review of the main parameters influencing

long-term performance and durability of PEM fuel cells,” J. Power Sources, 180,

1–14, 2008.

[2] X. Yuan, H. Wang, J. Colin Sun, and J. Zhang, “AC impedance technique in PEM

fuel cell diagnosis-A review,” Int. J. Hydrogen Energy, 32, (17), 4365–4380,

2007.

[3] S. Hershkovitz, S. Tomer, S. Baltianski, and Y. Tsur, “ISGP: Impedance

Spectroscopy Analysis Using Evolutionary Programming Procedure,” 33 (40),

67–73, 2011

[4] A. Oz, D. Gelman, E. Goren, N. Shomrat, S. Baltianski, and Y. Tsur, “A Novel

Approach for Supercapacitors Degradation Characterization,” Journal of Power

Sources, 355, 74-82, 2017.

Figuer1: A typical DFRT model of PEMFC

Mass Transport in Electrocatalysis: the Role of Nanostructure

Dr. David Eisenberg

Schulich Faculty of Chemistry, and the Grand Technion Energy Program,

Technion – Israel Institute of Technology

Electrocatalysis is at the intersection between electrochemistry, materials science, and catalysis.

Many energy conversion and storage devices rely on electrocatalysts to convert electricity to

molecular bonds, or vice versa. In developing new electrocatalysts and understanding their activity,

the concept of the catalytic site (or “active site”) plays a major role. This is where the magic

happens: reactants bind, electrons flow, products leave.

However, the environment of the catalytic site is key in understanding electrocatalytic activity. The

catalysts’ nanostructure determines crucial factors such as surface area (and hence, exposure of

active sites), distribution of conductive domains (and thus, the ‘wiring’ of the active sites), mass

transport of reactants/products to/from the active site, and even the wetting properties of the

catalyst powder.

Using doped carbons as our benchmark catalyst, we have recently discovered some surprising

examples for the importance of nanostructure on electrocatalysis. New strategies for inducing and

controlling carbon nanostructures allowed us to study synthesis–structure–activity correlations in

fuel cell reactions such as hydrazine oxidation and oxygen reduction.

FROM "NANO TO NANO": A NEW APPROACH FOR ELECTROCHEMICAL DEPOSITION

Daniel Mandler*, Ori Geuli and Liang Liu

Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel

*e-mail: Daniel.mandler@mail.huji.ac.il Electrochemical deposition (ED) dates back to Faraday and is a well-established approach for producing coatings. This presentation will summarize novel ED approaches, where nanostructured films are formed, starting with nanomaterials as building blocks, instead of molecular or ionic species. This “nano to nano” deposition concept has a significant advantage of directly transferring nano-objects from the dispersion to the coating, which maintains their unique nanoscale properties. It is achieved via destabilizing the nano-objects in the dispersions by applying electrochemical potential or current, which diminishes interparticle repulsion. Three different mechanisms have been explored, so far, for the ED of nanomaterials: (a) Direct redox induced deposition; (b) Indirect pH and ionic strength induced deposition; (c) Matrix induced co-deposition. With the latter two mechanisms, the “nano to nano” approach can be applied to electrochemically inactive and non-conductive nanomaterials. The deposition process is selective to conductive substrates and can be manipulated by potential/current and time, yielding films with thickness from nanometers to a few micrometers. A variety of examples will be presented spanning from organic to inorganic nanomaterials and used in applications such as coating of medical implants and more. Furthermore, we will show how such deposited nanomaterials can be used as carriers. References [1] R. Shacham, D. Avnir, D. Mandler, Adv. Mater. 1999, 11, 384-388. [2] I. Levy, S. Magdassi, D. Mandler, Electrochim. Acta 2010, 55, 8590-8594. [3] L. Liu, M. Layani, S. Yellinek, A. Kamyshny, H. Ling, P. S. Lee, S. Magdassi, D. Mandler, J. Mater. Chem. A 2014, 2, 16224-16229. [4] O. Geuli, N. Metoki, N. Eliaz, D. Mandler, Adv. Funct. Mater. 2016, 26, 8003-8010. [5] P. K. Rastogi, S. Sarkar, D. Mandler, Applied Materials Today, 2017, 8, 44-53. [6] O. Geuli, N. Metoki, T. Zada, M. Reches, N. Eliaz, D. Mandler, J. Mater. Chem. B, 2017, 5, 7819-7830. Acknowledgment: This research is [partially supported by grants from the National Research Foundation, Prime Minister’s Office, Singapore under its Campus of Research Excellence and Technological Enterprise (CREATE) programme.

Dental implant coated by the "nano to nano" approach by hydroxyapatite nanoparticles

Electrocatalytic Reduction of CO2 and Oxidation of CO Catalyzed by

Polyoxometalates

Dima Azaiza-Dabbah and Ronny Neumann

Department of Organic Chemistry Weizmann Institute of Science, Rehovot, Israel

Email:azaiza.dima@weizmann.ac.il

It is known that the greenhouse effect is highly influenced by the concentration of CO2 in the atmosphere. The

sources of CO2 are: power generation, public electricity and heat production from fossil fuel combustion. Previous

research shows different ways to reduce CO2 emission into the atmosphere, by reduction of the amount of CO2

produced, use of CO2, and storage of CO2 1-2.

There are many organometallic complexes that can be used as catalyst for CO2 reduction but these complexes

have some disadvantages: Some transition metals are rare and expensive, part of them are not stable during the

electrocatalytic reduction reaction and the synthesis of the ligand might be complicated. In this research, we try

to reduce CO2 with other kind of structures that called polyoxometalates. Polyoxometalates are soluble, generally

anionic, metal oxide oligomers formed by oxo species of high valent transition metals (W(VI), Mo(VI), V(V)

with one or more bridging oxygen atoms. The interest in polyoxometalate chemistry is largely due to their variety

of structures, sizes, redox activity, solubility, and thermal stability. Different structures of polyoxometalates have

been described, one of them the Keggin structure [XM12O40]n. Multiple lacunary structures obtained by removal

of MO units of the Keggin structure are also known 3-6.

The main goal of the project was to first prepare as series of tri-transition metal substituted Keggin type

polyoxometalates containing Cu(II), Fe(III) and Ni(II) and combinations three of, but more importantly to appraise

the activity of these compounds as electrocatalysts for the reduction of CO2. Thus, we have found that the

trimetallo Cu(II) substituted polyoxometalate shows a catalytic peak in the presence of CO2. After 15 h of bulk

electrolysis of CO2 at -2.5 V we obtained CO selectively, with a total TON of ~4x106 and a TOF=76 s-1 calculated

relative to the surface area of the electrode and faradaic efficiency of 94%. These values are the highest values

compared to other isostructural first row transition metals polyoxometalates that we synthesized. When evaluating

the activity of the polyoxometalates based on Fe(III) and Ni(II) and combinations thereof, we observed that the

high TOF values obtained from the CV measurements were not observed in the controlled electrolysis experiments

and in some case no CO or any other reduced product was observed. Since, one of the known enzymes for CO2

reduction has a Fe-Ni active site, and this enzyme also oxidizes CO to CO2 at higher rates, we suspected that this

is also a possible explanation for the reduced formation of CO and the low faradaic efficiency in the controlled

potential electrolysis experiments.

References:

1. M. Mikkelsen, M. Jørgensen and F. C. Krebs, Energy Environ. Sci., 2010, 3, 43–81.

2. M. Cokoja, C. Bruckmeier, B. Rieger, W. A. Herrmann and F. E. Kuhn, Angew. Chem. Int. Ed, 2011,

50, 8510-8537.

3. M. T. Pope, Heteropoly and Isopoly Oxometalates, 1983, Springer-Verlag: New York.

4. L. C. W. Baker, J. S. Figgis, J. Am. Chem. Soc. 1970, 92, 3794.

5. N. H. Nsouli, A. H. Ismail, I.S. Helgadottir, M.H. Dickman, J.M. Clemente-Juan, U. Kortz, Inorg,

Chem, 48,5884, (2009).

6. E. Haviv, D. Azaiza-Dabbah, Raanan Carmieli, Liat Avram, Jan M. L. Martin, Ronny Neumann,

Journal of the American Chemical Society, 2018, 140 (39),12451-12456.

Electrocatalytic CO2 Reduction Exhibited by Confined CoTMPyP in Electrodeposited Reduced Graphene Oxide

Y. Bochlin, E. Korin, and A. Bettelheim

Chemical Engineering Department, Ben-Gurion University of the Negev, P.O.Box 653, Beer-Sheva 84105, Israel yairboch@post.bgu.ac.il

The constantly increasing atmospheric CO2 is one of the largest environmental concerns facing our civilization today. CO2 is the most significant greenhouse gas that has major effects on the environment such as global warming and ocean acidification. The conversion of CO2 back to useful fuels and chemicals is a critical goal that would restore balance to earth’s atmosphere. CO2 reduction is possible through chemical catalysis, electrochemistry, photochemistry and biological processes. Chemical catalytic processes generally operate at high temperatures and pressures which lead to high energy cost. Electrochemical methods, however, operate at ambient conditions which offer a simple and effective route for CO2 reduction. The electrocatalytic capabilities toward CO2 reduction of some cobalt porphyrins have been reported in the literature, although at considerable overpotentials and low current densities. The present work aims to assemble an electrocatalytic system composed of cobalt porphyrins and graphene derivatives. Spectroscopic, microscopic and electrochemical methods are used to analyze the interactions occurring between such porphyrins and graphene derivatives, and their effect on CO2 reduction. Such self-assembled systems are formed between 5,10,15,20-Tetrakis(1-methyl-4-pyridinio) porphyrin (CoTMPyP) and graphene oxide (GO). This combination was electrodeposited on electrode surfaces, from aqueous solutions, using concessive cyclic voltammetry scans. Cross-section TEM-EELS images found dense distribution of CoTMPyP between the reduced graphene oxide (rGO) sheets throughout the coating. This arrangement of dense cobalt porphyrins between large conducting graphene sheets leads to enhanced electrocatalytic activity for CO2 reduction as examined in aqueous 0.1M Na2CO3 solutions. The catalytic system exhibits a current density of 3.4 mA cm-1 (faradaic efficiency of 45.0%, 24.3% and 28.5% for CO, formate and H2, respectively) at -0.7V vs. RHE, corresponding to a turnover frequency (TOF) of 1.48 s-1 and a turnover number (TON) 32000 after 6 hours.

Utilizing photosynthetic organisms and isolated complexes for direct solar energy conversion: building Bio-photoelectrochemical cells.

Noam Adir

aSchulich Faculty of Chemistry, Technion, Haifa Israel; noam@ch.technion.ac.il

Photosynthetic organisms, membranes and complexes are attractive starting

materials for solar energy conversion (SEC). Our overall goal is to develop methods to

perform SEC using these materials in simple, inexpensive and a fashion that will be non-

polluting and will not compete with the growth of food materials. I will describe here

how the remarkable photocatalytic activity of the photosynthetic apparatus can provide

overall water splitting with oxygen and hydrogen production in Bio-Photo-Electro-

Chemical (BPEC) cells via the simplest and cleanest of processes wither in the absence of

presence of added electron transport molecules. With plant thylakoids, electrons are

shuttled by FeCN to a transparent FTO electrode, yielding a photocurrent density of 0.5

mA·cm-2. Hydrogen evolution occurs at the cathode at a bias as low as 0.8 V. A tandem

cell comprising the BPEC cell with the thylakoid membranes and a Si photovoltaic

module achieves overall water splitting with solar to hydrogen conversion efficiency of

0.3% (Pinhassi et al. Nature Communications 2016). With cyanobacterial cells, following

a brief treatment that does not kill the cells, electrons from both the respiratory and

photosynthetic systems are transferred directly to a graphite electrode, utilizing

endogenous electron carriers (Saper et al. Nature Communications 2018). The current

produced can be used for hydrogen production at low additional bias for significantly

longer durations than the plant thylakoids. BPECs that utilize isolated photosynthetic

complexes will also be described.

REDUCED GRAPHENE OXIDE -MODIFIED MICROELECTRODE FOR ANTIPSYCHOTIC OLANZAPINE REAL-TIME DETECTION IN BLOOD

Rajendra P. Shukla, Remi Cazelles, and Hadar Ben-Yoav*,

Nanobioelectronics Laboratory (NBEL), Department of Biomedical Engineering, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel

*e-mail: benyoav@bgu.ac.il Olanzapine (OLZ) is a thienobenzodiazepine compound [1]. It is one of the newer types of antipsychotic drugs used in the treatment of schizophrenia and other psychotic disorders. Several methods have been reported for the analysis of OLZ in its pure form or in combination with other drugs and in biological fluids, including high-performance liquid chromatography and liquid chromatography-tandem mass spectroscopy [2]. Although, many of the reported methods are accurate and sensitive, they require the use of sophisticated equipment, lack the demonstration of in situ analysis capabilities, and require expensive reagents. Some are cumbersome, requiring prolonged sample pre-treatment, strict control of pH and long reaction times. Here we present the development of a miniaturized electrochemical sensor that allows a minimally invasive, real-time and in situ monitoring of OLZ levels in microliter volume of serum samples. We modified a microfabricated microelectrode with a reduced graphene oxide (r-GO) film (Figs. 1A, 1B & 1C). The modification increased the electrocatalytic activity of the microelectrode towards OLZ oxidation and improved the overall selectivity of the sensor. Differential pulse voltammetry technique was used to measure the OLZ (70-150 nM) oxidation currents with the r-GO -modified microelectrode in microliters volume of undiluted serum (Fig. 1D). We observed a characteristic dose response effect (Fig. 1E) that resulted in a limit-of-detection of 20.0 ± 3.2 nM and a sensitivity of 7.5 ± 0.4 A/M whereas the bare microelectrode was unable to differentiate between the different doses of OLZ. Importantly, the r-GO –modified microelectrode demonstrated a limit-of-detection below the required clinical threshold (65 nM). Our preliminary work anticipates production of miniaturized and wearable testing devices, designed for schizophrenia treatment management.

Figure. 1. (A) Scheme of an in situ detection of OLZ in undiluted serum, (B) cyclic voltamograms of r-GO modification process, (C) Optical image of the microelectrodes modified with r-GO, bare, and on chip Ag/AgCl reference microelectrode, (D) OLZ detection using r-GO -modified microelectrode in 20 µL of undiluted serum, and (E) OLZ dose response characteristics for the r-GO -modified microelectrode. References [1] J. T. Callaghan et al, Clin. Pharmacokinet., 1999, 37, 177–193. [2] L. J. Dusci et al, J. Chromatogr. B: Anal. Technol. Biomed., 2002, 773,191–197. Acknowledgements The authors thank the Brain and Behaviour Research Foundation (Grant No. 26038) for funding the

Project and IIse Katz Institute for Nanoscale Science and Technology at Ben‐Gurion University of the Negev, for their help in microelectrode microfabrication and material characterization. The authors also thank the Krietman School for Mid-way Negev fellowship and Marcus Postdoctoral Fellowships in Water Sciences Program for their support.

Electron Transfer in Coordination-based Molecular Assemblies

Michal Lahav Weizmann Institute of Science, Department of Organic Chemistry, 761001, Rehovot, Israel

Email: michal.lahav@weizmann.ac.il

Directional electron-transfer events are the basis of many technologically important systems and biological processes. We demonstrate how the distance over which electron transfer occurs through organic materials can be controlled and extended. Coating of conductive surfaces with nanoscale layers of redox-active metal complexes allows the electrochemical addressing of additional but distant layers that are otherwise electrochemically silent. We also show that our composite materials can pass electrons selectively in directions that are determined by the positioning of redox-active metal complexes and the distances between them. These electron-transfer processes can be made dominantly uni- or bidirectional. Our design strategy involves 1) a set of isostructurally well-defined metal complexes with different electron affinities, 2) a scalable metal-organic spacer, and 3) a versatile assembly approach that allows systematic variation of material composition, structure, and electron transfer properties. We control the electrochemical communication between interfaces by the deposition sequence of the components and the length of the spacer, and therefore we are able to program the bulk properties of the assemblies, including their color.

Figure 1. Examples of rerouting electron transfer by composite molecular materials

References (1) Balgley, R.; Algavi, Y.; Elool Dov, N.; Lahav, M.; van der Boom, M. E. Angew. Chem., Int. Ed.

2018, 57, 1–7. (2) Balgley, R.; Shankar, S.; Lahav, M.; van der Boom, M. E. Angew. Chem., Int. Ed. 2015, 54,

12457–12462. (3) Malik, N.; Elool Dov, N.; de Ruiter, G.; Lahav, M.; M. van der Boom, M. E. ACS Appl. Mater.

Interfaces 2019, 11, 22858–22868.

HIGHLY EFFICIENT FLAVIN–ADENINE DINUCLEOTIDE GLUCOSE DEHYDROGENASE FUSED TO A MINIMAL CYTOCHROME C DOMAIN

I. Algov 1*

, J. Grushka 1, R. Zarivach

1, L. Alfonta

1

1 Department of Life Sciences and Ilse Katz Institute for Nanoscale Science and Technology

* algov@post.bgu.ac.il As the incidence of Type 1 and Type 2 Diabetes rise around the world, there is a constant improvement of blood-glucose monitoring tools. Some glucose biosensing instruments utilize Flavin-adenine dinucleotide dependent glucose dehydrogenase (FAD-GDH) as a glucose oxidizing enzyme. FAD-GDH does not use oxygen as its final electron acceptor, and is thermostable, which renders it a good candidate for enzyme-based glucose biosensors. Electrons from the redox active catalytic site of the enzyme are entrapped within the insulating protein matrix and cannot be transferred directly to an electrode. In this study, natural minimal C-type cytochrome domain was fused to the c-terminus of FAD-GDH, in order to achieve direct electron transfer abilities. Our new fusion enzyme introduced highly efficient direct electron transfer compared to the native enzyme, with ca. seven times higher catalytic current, three times higher kcat and lower onset potential. The onset potential of the new enzyme is about (-)0.15 V vs. Ag/AgCl reference electrode. This low potential is beneficial since it diminishes the electrode sensitivity to known interfering molecules such as Vitamin C that is being oxidized at the electrode at higher redox potentials. To conclude, the fusion enzyme can simplify glucose biosensing, it is highly sensitive and selective towards glucose and thus can be utilized in blood-glucose monitoring.

Hydrogen-Bromine Redox-Flow batteries

K. Saadi, S. Hardisty, Z. Tatus Portnoy, P. Nanikashvili, D. Zitoun

Department of Chemistry and Bar Ilan Institute of Nanotechnology and Advanced Materials (BINA), Bar

Ilan University, Ramat Gan 5290002, Israel

Hydrogen-bromine redox-flow batteries (RFBs) technology offers the most economic storage

solution and is considered most promising for a sustainable electricity storage solution due to its

fast kinetics, highly reversible reactions and low chemical costs. The main bottleneck of

conventional electrodes is the rapid fading of the hydrogen catalyst performance in the highly

corrosive environment.

The crossover of Br species requires the use of a catalyst with a high PGM (platinum group metals).

To increase the effectiveness of the storage system, the catalyst cost needs to be decreased (by

reducing the PGM loading) whilst increasing its tolerance versus bromide species. To solve this

dilemma, we investigate the combination between PGM and non-PGM metals at the nanoscale

with a polymeric surface coating. We show that a 1 nm thin coating on the catalyst can effectively

protects the metallic surface from corrosion in concentrated HBr and maintains a high catalytic

activity.

References:

PCT Application No. PCT/IL2018/050254

From the Sea to Hydrobromic Acid:

Polydopamine Layer As Corrosion Protective

Layer on Platinum Electrocatalyst ACS Appl.

Energy Mater., 2018, 1 (9), pp 4678–4685

Crossover-Tolerant Coated Platinum Catalysts in

Hydrogen/Bromine Redox Flow Battery J. Power

Sources 2019, 422, 84

Figure: Illustration of the protective coating on the catalyst nanoparticle which allows a free diffusion of hydrogen

species and blocks bromide species

3D-PRINTED FUNCTIONAL MATERIALS FOR ELECTROCHEMICAL ENERGY STORAGE

Heftsi Ragones1, Yosi Kamir1, Adi Vinegrad1, Meital Goor1, Lina Faktorovich1, Gilat Ardel1,

Svetlana Menkin1, Arie Simkhovich1,2, Diana Golodnitsky1,2

1 School of Chemistry

2 Wolfson Applied Materials Research Center Tel-Aviv University, Tel-Aviv, 69978, Israel

e-mail: heftsira@post.tau.ac.il

The increasing demand for multifunctional portable/wearable electronic devices, including wireless sensors and implantable medical devices is continuously growing. Such devices need rechargeable batteries with dimensions on the scale of 1–10 mm3 (few to tens mm2 footprint area of substrate) including all the components and all the associated packing. Thus, in the past decade, along with the developments in battery materials, the focus has been shifting more and more towards innovative fabrication processes, unconventional configurations, and designs with multi-functional components. 3D printing technologies enable a well-controlled creation of functional materials with three-dimensional architectures, representing a promising approach for fabrication of next-generation electrochemical energy storage (EES) devices with high performance due to a higher electrode/electrolyte interfacial area. In this work, we demonstrate a novel design and a novel approach of 3D printing of batteries of different shapes and size by using filaments composed of active electrode materials bound with polymers. The electrodes were printed by fused-filament fabrication (FFF) method. We demonstrated a reversible electrochemical cycling of 3D printed lithium iron phosphate (LFP) and lithium titanate (LTO) composite polymer electrodes vs. lithium metal anode with high performance and capacity in cells containing both conventional non-aqueous and ionic-liquid electrolytes. In addition, the development and fabrication of a novel 3D-printed solid-state or quasi-solid electrolyte by FFF has been accomplished. The electrolytes are composed primarily of polyethylene oxide (PEO) and polyethylene glycol (PEG) which are known ionic conductors, and poly lactic acid (PLA) for enhanced mechanical properties and high temperature durability. Our research introduces novel thick-layer 3D batteries, thus reducing cost related to high mass loading per battery footprint of smart 3D structures with the help of low-cost fabrication method. References [1] Ragones, Heftsi, et al. "Towards smart free form-factor 3D printable batteries." Sustainable Energy & Fuels 2.7 (2018): 1542-1549.

Metallo‐Organic Assemblies for Dual-Function

Electrochromic Supercapacitors

Ofir Eisenberg*, Yadid Algavi, Haim Weissmann, Michal Lahav and Milko E. van

der Boom

Weizmann Institute of Science, Department of Organic Chemistry, 7610001,

Rehovot. Email: ofir.eisenberg@weizmann.ac.il

The rapid and global increase in green energy demands has driven the research and

development of alternative and efficient energy storage materials and devices.1 Energy

storage systems can be divided to two main categories: batteries and capacitors.2

Batteries have a high energy density, whereas capacitors have a high power density.

Hybrid supercapacitors combine battery-like and capacitive electrodes. This

combination allows the best of both worlds: high power and high energy density. The

replacement of conventional inorganic materials (eg. lithium, lead, antimony,

cadmium) by molecular based materials is expected to result in flexible, readily

available devices with enhanced functionalities.

We introduced a hybrid device which is composed of carbon nanotubes (CNTs)

and PSS:PEDOT, as the counter electrode,3 and metallo-organic assemblies (MA), as

the working electrode. Our MA are robust, showed high stability in a non-inert

environment at high temperatures. These assemblies can be deposited directly on

conductive substrates. During the oxidation of the MA at the working electrode, the

charge will be stored by the CNTs deposited on the counter electrode. We take

advantage of the fact that our MA are electrochromic4 (i.e. change their optical

properties with respect to an applied potential) to generate dual-function devices. These

devices indicate their charge state by their color.

References

1. Muzaffar, A.; Ahamed, M. B.; Deshmukh, K.; Thirumalai, J. A Review on Recent Advances in

Hybrid Supercapacitors: Design, Fabrication and Applications. Renew. Sustain. Energy Rev.

2019, 101, 123–145.

2. Dubal, D. P.; Ayyad, O.; Ruiz, V.; Gómez-Romero, P. Hybrid Energy Storage: The Merging of

Battery and Supercapacitor Chemistries. Chem. Soc. Rev. 2015, 44, 1777– 1790.

3. Zhai, Y.; Dou, Y.; Zhao, D.; Fulvio, P. F.; Mayes, R. T.; Dai, S. Carbon Materials for Chemical

Capacitive Energy Storage. Adv. Mater. 2011, 23, 4828–4850.

4. Elool Dov, N.; Shankar, S.; Cohen, D.; Bendikov, T.; Rechav, K.; Shimon, L. J. W.; Lahav, M.;

van der Boom, M. E. Electrochromic Metallo-Organic Nanoscale Films: Fabrication, Color

Range, and Devices. J. Am. Chem. Soc. 2017, 139, 11471–11481.

INVESTIGATION OF NOVEL N-HETROCYCLIC LITHIUM SALT DISSOLVED IN SILANE-BASED SOLVENT AS A SAFE ELECTROLYTE FOR HIGH POWER

LITHIUM BATTERIES

Y. Horowitz1, T. Assa Chernobyl1, J. Kasnatscheew2, M. Grünebaum2, M. Winter2, D. Golodnitsky1,3, E. Peled*1

1School of Chemistry, Tel Aviv University, Tel Aviv 6997801, Israel, 2Helmholtz-Institute Münster, IEK-12, Forschungszentrum Jülich GmbH, Corrensstraße 46, 48149 Münster, Germany, 3Wolfson Applied

Materials Research Center, Tel Aviv University, Tel Aviv, 69978, Israel *e-mail: peled@tauex.tau.ac.il

The chemical compatibility of the various compounds and elements used in lithium-based

batteries dictates their safe operation parameters and performance. Here we focus on the functional design and optimized syntheses of a novel family of siloxane-based battery solvents[1] and a new generation of lithium conducting salts (see Figure 1) with improved thermal, electrochemical stability, high ionic conductivity and long-life stability caused by a well-tailored solid electrolyte interphase (SEI).

Figure 1. BF3-modified lithium pyrazolide salt.

Aprotic solvents based on silicon oxygen bonds (e.g., siloxane Si-O-Si or silane Si-O) are promising candidates to replace current carbonate-based solvents as they are less flammable. In addition, silane-based solvents provide adequate ionic conductivities over a broad temperature range and sufficient electrochemical stabilities, thus we can apply these solvents to high voltage cathode batteries. Nowadays, the most commonly used lithium salt is LiPF6 having several disadvantages, namely its reactivity in relation to moisture and the insufficient thermal and electrochemical stability (<5 V vs. Li/Li+)[2]. However, to successfully compete with state-of-the-art electrolytes, the ability to form an effective SEI layer is essential. In frame of the project, siloxane-based compounds, together with N-heterocyclic lithium salts have been synthesized and investigated with the particular focus on the SEI forming.

The salt at hand was synthesized with sterically demanding groups[3]. These groups simultaneously give rise to several positive effects: a) increased salt dissociation thus increasing the mobile "free" charge carriers, b) better electrochemical stability as the shielding by the N-heterocyclic nuclei prevents dissociation pathways (e.g., with themselves, other solvent molecules or electrode surfaces). Lastly, the sterically demanding group can be tailored as special “built-in” groups to form SEI on anode materials.

In this talk, we will present our findings on BF3 modified lithium pyrazolide salt dissolved in 3-Cyanopropyldimethoxysilane (3-CDS) characterized on Si-based anodes. References [1] Y. Horowitz, I. Ben-Barak, D. Schneier, M. Goor-Dar, J. Kasnatscheew, P. Meister, M.

Grünebaum, H.-D. Wiemhöfer, M. Winter, D. Golodnitsky, E. Peled, Study of the Formation of a Solid Electrolyte Interphase (SEI) on a Silicon Nanowire Anode in Liquid Disiloxane Electrolyte with Nitrile End Groups for Lithium-Ion Batteries, Batter. Supercaps. 307 (2019) 76–82. doi:10.1002/batt.201800123.

[2] G. Cauquis, D. Serve, The nature of the radical observed during the electrochemical oxidation of some perchlorate solutions in organic media, J. Electroanal. Chem. Interfacial Electrochem. 27 (1970) A3–A6. doi:10.1016/S0022-0728(70)80227-3.

[3] J. Clayden, N. Greeves, S. Warren, P. Wothers, Organic Chemistry, Oxford University Press, United States, 2001, pp. 139.

Acknowledgments This work is funded by the German Israeli Battery School (GIBS) program, grant No. 00040024000. YH is supported by the Shamir Fellowship, graciously granted by Israel’s Ministry of Science and Technology.

Emerging Innovations in Material Characterizations for Energy Storage and Conversion Using EQCM-D

Netanel Shpigel

Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel

E-mail: nshpigel@gmail.com

Depending on a variety of factors (electrode thickness, morphology, mechanical properties such as stiffness/compliance), the quartz crystal resonator coated with thin electrode coatings oscillates in a typically MHz frequency range on multiple harmonics operating in either gravimetric or beyond-the-gravimetric modes. The latter mode provides important real time information about the mechanical properties of the electrodes during their charging/discharging. Starting from a simple gravimetric monitoring of dynamics of ions adsorption into nanoporous carbon supercapacitors, 1 we have further proved that the use of multiharmonic Electrochemical Quartz Crystal Microbalance with Dissipation Monitoring (EQCM-D) provides the basis for the new powerful in situ method of highly sensitive monitoring of intercalation-induced dimensional and porous structure changes in operating battery 2 and supercapacitor 3 electrodes. The resonance frequency and dissipation factor changes caused by contact of a porous solid electrode with electrolyte solutions are recorded on multiple harmonics and fitted to a suitable hydrodynamic impedance model returning structural parameters of the electrode. In the second step, this new methodology was extended to a continuous monitoring of gravimetric, dimensional and viscoelastic changes of binder-free 2D electrodes such as MXene (Ti3C2(OH)x) caused by insertion of water molecules modulated by intercalation-deintercalation of Li-ions in aqueous solutions. 4-7 Monitoring viscoelastic properties of solid-electrolyte interface (SEI) formed on the surface of a high-voltage anode such as LTO was shown to be an extremely effective means for fast screening of electrolyte solutions to optimize the cycling behavior of this electrode. 8 Our recent paper made focus on in situ acoustic diagnostics of particle-binder interactions in battery electrodes: the accommodation of intercalation-induced volume changes significantly depends on the stiffness/softness of the binder used, 9 on one hand, and on the extent to which the size of the guest cation matches the size of the host accommodation sites. 10 The different worked examples of the successful use of EQCM-D-based surface-acoustic-wave spectroscopy for material characterization of energy storage electrodes have been summarized in a recent review. 11 More examples of innovative methods of material characterizations by QCM-D will be presented in the talk.

References

1. M.D Levi, G. Salitra, N. Levy, D. Aurbach, J. Maier, Nature Materials, 2009, 8, 872-875. 2. N. Shpigel, M.D. Levi, S. Sigalov, O. Girshevitz, L.Daikhin , D.Aurbach, P. Pikma, M.Marandi, A. Jänes, E. Lust, N.

Jäckel, and V. Presser, Nature Materials, 2016 , 15, 570-575. 3. N. Shpigel, M.D. Levi, S. Sigalov, L.Daikhin, D.Aurbach, and V. Presser, J. Phys.: Condens. Matter (2016) 28,

114001. 4. M.D. Levi, M.R. Lukatskaya , S. Sigalov, M. Beidaghi, N. Shpigel, L. Daikhin, D. Aurbach, M.W. Barsoum, Y.Gogotsi,

Adv. Energy Mater. 2014, 1400815. 5. N. Shpigel, M. R. Lukatskaya, S. Sigalov, Chang E. Ren, P. Nayak, M. D. Levi, L. Daikhin, D. Aurbach, Y. Gogotsi, ACS

Energy Lett. 2017, 1407–1415. 6. M. R. Lukatskaya, Sankalp Kota, Zifeng Lin, Meng-Qiang Zhao, N. Shpigel, M. D. Levi, J. Halim, P.-L. Taberna, M. W.

Barsoum, P. Simon, Y. Gogotsi, Nature Energy, 2017, 2, 17105. 7. N. Shpigel, M. D. Levi, S. Sigalov, T. S. Mathis, Y. Gogotsi, D. Aurbach, J. Am. Chem. Soc., 2018, 140, 8910-8917. 8. V. Dargel, N. Shpigel, S. Sigalov, P. Nayak, M.D. Levi, L. Daikhin, D. Aurbach, Nature Communications, 2017, 1389. 9. V. Dargel, N. Jäckel, N. Shpigel, S. Sigalov, M.D. Levi, L. Daikhin, V. Presser, D. Aurbach, In Situ Multilength-Scale

Tracking of Dimensional and Viscoelastic Changes in Composite Battery Electrodes, ACS Applied Materials & Interfaces 2017, 27664–27675.

10. N. Shpigel, S. Sigalov, Mikhael D.Levi, T. Mathis, L. Daikhin, A. Janes, E. Lust, Y. Gogotsi, D. Aurbach, In Situ Acoustic Diagnostics of Particle-Binder Interactions in Battery Electrodes, Joule 2018, 2, 988.

11. N. Shpigel, M.D. Levi, S. Sigalov, O. Girshevitz, L.Daikhin , D. Aurbach. Acc. Chem. Research, 2017, 51, 69-79.

OPERANDO CHARACTERIZATION OF CHARGE EXTRACTION

PROFILES IN SEMICONDUCTOR PHOTOELECTRODES WITH

NANOSCALE RESOLUTION

Gideon Segev1,2,3a, Hen Dotan3, David S. Ellis3, Yifat Piekner3, Dino Klotz3, Jeffrey W. Beeman1,

Jason K. Cooper1, Daniel A. Grave3, Chang-Ming Jiang1,4, Gregory Zaborski1, Francesca M.

Toma1, Ian D. Sharp1,4, and Avner Rothschild3

1Joint Center for Artificial Photosynthesis, Lawrence Berkeley National Laboratory, Berkeley,

CA USA 2School of Electrical Engineering, Tel Aviv University, Tel Aviv, Israel

3Department of Materials Science and Engineering, Technion – Israel Institute of Technology,

Israel 4Walter Schottky Institut and Physik Department, Technische Universität München, Garching,

Germany

ABSTRACT

Detailed understanding of the opto-electronic properties of semiconductors, as well as of the

driving forces and loss mechanisms that limit device performance, is essential to the

development of high efficiency solar energy conversion and storage systems. However, many

photovoltaic and photoelectrochemical systems are difficult to model and only few experimental

methods are available for direct characterization of dominant loss processes under relevant

operating conditions. To this end, empirical extraction of the spatial collection efficiency (SCE)

is an operando, analytical tool to study new materials and devices. Defined as the fraction of

charge carriers that are photogenerated at a given location that contribute to the measured

current, the SCE provides a functional depth profile of the active regions in the device. By

combining incident photon to current efficiency (IPCE) measurements with optical modeling,

we have extracted SCE cross-sectional profiles of several photoelectrode materials for

photoelectrochemical water splitting.

SCE extraction provides an in-depth understanding of the driving forces and limiting mechanisms

in new materials with relatively simple apparatus. For example, analyzing the SCE at different

operating potentials while performing different photoelectrochemical reactions allows

distinguishing between bulk and surface losses. By focusing on the SCE at the surface, we were

able to discern between surface losses attributed to slow reaction kinetics and fast surface

recombination processes through charged band states. Furthermore, by comparing front and back

illuminated IPCE spectra, we extracted the wavelength dependent probability to excite mobile

charge carriers. In this contribution, we show how different transport and loss mechanisms can be

quantified through SCE extraction. We analyze the transport properties of hematite and four

different phases of copper vanadate photoanodes with a wide range of copper/vanadium ratios.

The SCE analysis is used to extract the potential dependent surface reactivity and collection

length. Exciton binding and d-d transitions are shown to yield formidable losses in all tested

metal oxide photoelectrodes.

a Corresponding author, gideons1@tauex.tau.ac.il

Selective charge trapping and release in nanoscale films Floriane Sturm*, Yonatan Hamo, Michal Lahav, and Milko van der Boom

The Weizmann Institute of Science, Department of Organic Chemistry, 761001 Rehovot, Israel. Email: florianesturm@online.de

We demonstrate selective charge trapping and release in nanoscale-thick layers of iron and osmium complexes. Electrochromic metallo-organic films are generated by Layer-by-layer spin-coating on transparent conductive oxides.1 These molecular assemblies consist of isostructural polypyridine complexes of bivalent ruthenium, iron and osmium which are cross-linked by coordination with palladium dichloride. We positioned these well-defined molecular layers on the electrode surface in such a manner that enable control over the charge trapping layer–identity. With ruthenium as electron-mediator directly attached to the electrode, we are exploring the photo-electrochemical properties of our films as well as redox and electrochromic behavior.2,3

References

(1) Elool Dov, N.; Shankar, S.; Cohen, D.; Bendikov, T.; Rechav, K.; Shimon, L. J. W.; Lahav, M.; van der Boom, M. E. Electrochromic Metallo-Organic Nanoscale Films: Fabrication, Color Range, and Devices. J. Am. Chem. Soc. 2017, 139, 11471–11481.

(2) Balgley, R.; Algavi, Y,; Elool Dov, N.; Lahav, M.; van der Boom, M. E. Light-Triggered Release of Trapped Charges in Molecular Assemblies Angew. Chem. Int. Ed. 2018, 57, 1-7.

(3) Malik, N.; Elool Dov, N.; de Ruiter, G.; Lahav, M.; van der Boom, M. E. On-Surface Self-Assembly of Stimuli-Response Metallo-Organic Films: Automated Ultrasonic Spray-Coating and Electrochromic Devices ACS Appl. Mater. Interfaces 2019, 11, 22858-22868.

ELECTROCHROMIC METALLO-ORGANIC FILMS: SPRAY-COATING, ON-SURFACE SELF ASSEMBLY, AND LAMINATED DEVICES

Naveen Malik, Neta Elool Dov, Michal Lahav and Milko E. van der Boom

Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot, Israel. Email: naveen.malik@weizmann.ac.il

Electrochromic materials (ECMs) reversibly change their optical properties when applying a potential. ECMs can find extensive applications in smart windows, sunglasses, anti-glare mirrors, display technology, etc. Various ECMs based on organic polymers, metallo-organic polymers, polyelectrolytes, transition metal oxides (TiO2, ZnO, WO3, etc.) have been studied for several decades. A combination of various factors still limit the large-scale commercial implementation of electrochromic windows,1 including fabrication cost, optical contrast, stability, low switching speed, and scalability. Recently, our group investigated the electrochromic properties of molecular assemblies formed from iron, ruthenium and osmium polypyridyl complexes using layer-by-layer (LBL) dip-coating or spin-coating methods.2 In this study, we demonstrate spray-coating for the formation of homogeneous and uniform electrochromic assemblies on transparent-conductive oxides (TCOs) on both rigid and flexible substrates with surface areas of up to 36 cm2. This fast and versatile process is suitable for the on-surface production of self-assembled 3D-networks with a high chromophore density using polypyridyl complexes and a metal salt. These films have been integrated into laminated electrochromic devices (ECDs) containing a gel electrolyte and a conductive polymeric layer as the charge storage layer. The ECDs have attractive ON/OFF ratios (50%) and electrochemical stabilities up to >1000 redox cycles. In this study, we also observed that, the performance/stability of the ECDs depends on the type of counter anion of the gel electrolyte. References [1] (a) Yan, X.; Wang, F.; Zheng, B.; Huang, F. Chem. Soc. Rev. 2012, 41, 6042-6065. (b) McConnell, A. J.; Wood, C. S.; Neelakandan, P. P; Nitschke, J. R. Chem. Rev. 2015, 115, 7729-7793. [2] (a) Elool Dov, N.; Shankar, S.; Cohen, D.; Bendikov, T.; Rechav, K.; Shimon, L. J. W.; Lahav, M.; van der Boom, M. E. J. Am. Chem. Soc. 2017, 139, 11471-11481. (b) Shankar, S.; Lahav, M.; van der Boom, M. E. J. Am. Chem. Soc. 2015, 137, 4050-4053. (c) Motiei, L.; Lahav, M.; Freeman, D.; van der Boom, M. E. J. Am. Chem. Soc. 2009, 131, 3468-3469.

Significance of H2O2 Photo-Oxidation in Water Splitting for Co-Catalyst Design

Yotam Y. Avital1, Hen Dotan2, Dino Klotz2, Daniel A. Grave2, Anton Tsyganok2, Bhavana Gupta1,

Sofia Kolusheva3, Iris Visoly-Fisher1, Avner Rothschild2, Arik Yochelis1,4

1Department of Solar Energy and Environmental Physics, Swiss Institute for Dryland Environmental and Energy Research, Blaustein Institutes for Desert Research (BIDR), Ben-Gurion University of the Negev, 8499000 Midreshet Ben-Gurion, Israel, 2Department of Materials Science and Engineering,

Technion – Israel Institute of Technology, 32000 Haifa, Israel, 3Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, 8410501 Be’er Sheva, Israel, 4Department of Physics, Ben-Gurion University of the Negev, 8410501 Be’er Sheva, Israel.

*e-mail: yochelis@bgu.ac.il H2O2 is a sacrificial reductant that is often used as a hole scavenger to gain insight into photoanode properties. Here we show a distinct mechanism of H2O2 photo-oxidation on haematite (α-Fe2O3) photoanodes. We found that the photocurrent voltammograms display non-monotonous behaviour upon varying the H2O2 concentration, which is not in accord with a linear surface reaction mechanism that involves a single reaction site as in Eley–Rideal reactions. We postulate a nonlinear kinetic mechanism that involves concerted interaction between adions induced by H2O2 deprotonation in the alkaline solution with adjacent intermediate species of the water photo-oxidation reaction, thereby involving two reaction sites as in Langmuir–Hinshelwood reactions. The devised kinetic model reproduces our main observations and predicts coexistence of two surface reaction paths (bi-stability) in a certain range of potentials and H2O2 concentrations. This prediction is confirmed experimentally by observing a hysteresis loop in the photocurrent voltammogram measured in the predicted coexistence range [1]. References [1] Y.Y. Avital, H. Dotan, D. Klotz, D.A. Grave, A. Tsyganok, B. Gupta, S. Kolusheva, I. Visoly-Fisher, A.

Rothschild, and A. Yochelis, Two site H2O2 photo-oxidation on haematite photoanodes, Nature

Communications 9, 4060 (2018) Acknowledgments This research was supported by the Ministry of National Infrastructures, Energy and Water Resources of Israel (grant no. 3-11430), the Ministry of Science and Technology of Israel (grant no. 3-14423), the European Research Council under the European Union’s Seventh Framework programme (FP/200702013)/ERC (grant agreement no. 617516), and the Adelis Foundation.

GOLD NANOPARTICLES AS A TOOL FOR PROBING CORROSION PROCESSES

Alexander Vaskevich1, Alexander B. Tesler1, Eyal Sabatani2, Takumi Sannomiya3, Israel Rubinstein1

1Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel, 3Chemistry Division, Nuclear Research Centre Negev, Beer Sheva, Israel, 3Department of Materials Science and Engineering, School of Materials Science and Engineering, Tokyo Institute of Technology, Yokohama, Kanagawa, Japan

*e-mail: alexander.vaskevich@weizmann.ac.il This work is dedicated to the memory of Prof. Israel Rubihstein.

Optical corrosion probes provide several advantages, enabling remote sensing, probing in variable

media (gas, liquid) and temperatures, and imaging with high spatial resolution. The optical properties (reflection, transmission) of plasmonic nanoparticles (NPs) in the proximity of a metal mirror strongly depend on the dielectric properties of the immediate environment, characteristic of localized surface plasmon resonance (LSPR) systems, and the separation between the NPs and the metal surface, forming a Fabry-Pérot interferometer with the plasmonic array.1-3 A plasmonic corrosion probe combines a film of corroding metal of interest and a chemically and morphologically stable plasmonic nanostructure (Au NP array).4 Au NPs can be immobilized on the surface of the chemically active metal by adsorption from a colloid solution, or deposited by vacuum evaporation as a film of Au nano-islands.One of such fields is corrosion monitoring.

We studied the corrosion of aluminum in hot water using the optical response of Au NPs immobilized on the chemically active metal surface. Oxidation of Al in water in the temperature range 40–100 oC produces a non-uniform hydroxide layer, with a dense layer adjacent to the metal and an outer porous part consisting of rough platelets of pseudoboehmite. High-resolution scanning electron microscopy (HRSEM) images of a fully oxidized plasmonic probes show that the oxide layer is more dense below the Au NPs and has a rough, open structure on the solution side (above the Au NPs), closely resembling the structure with no plasmonic layer. The Au NP layer embedded in the oxide preserves its integrity, while the separation between the Au NPs and the glass after complete corrosion of the Al film remains nearly constant for Au NPs evaporated or immobilized from solution. Cross-sectional HRSEM and transmission electron microscopy (TEM) images show that the separation between the plasmonic layer and the corroding metal increases with time while preserving the morphology of the oxide layer.

Corrosion of plasmonic probes exhibits large changes in the reflection spectra. The changes were measured quantitatively in-situ using a conventional fiber-optics system. In the course of the Al corrosion the visual appearance (color) of the probe continuously varies. Changes in the reflection spectra and the probe color can be quantified, allowing evaluation of the propagation of the corrosion front. The high color contrast also allows visualization of lateral inhomogeneities in the corroding layer. The combination of plasmonic probes and image processing opens the possibility of simultaneous measurement of local corrosion rates over a macroscopic area.

Plasmonic corrosion probes are simple to implement, while the results may be useful in the design of effective optical sensors for practical applications. With certain modifications, the plasmonic corrosion probe approach may be applicable to other active metals of practical importance. References [1] Aussenegg, F. R.; Brunner, H.; Leitner, A.; Lobmaier, C.; Schalkhammer, T.; Pittner, F. Sensors and Actuators B-Chemical 1995, 29, 204. [2] Sannomiya, T.; Balmer, T. E.; Heuberger, M.; Voros, J. J. Phys.D-Applied Physics 2010, 43. [3] Kedem, O.; Sannomiya, T.; Vaskevich, A.; Rubinstein, I. J. Phys. Chem. C 2012, 116, 26865. [4] Tesler A, Sabatany E., Sannomiya T., Vaskevich A, Rubinstein I., Adv. Opt. Mater. 2018, 6, 1800599.

Poster Presentation Abstracts

ROBUST DNA RECOGNITION INTERFACE

A. Solomonov, 1,* A. Vaskevich, 1 I. Rubinstein #

1Department of Materials & Interfaces, Weizmann Institute of Science, Rehovot 7610001, Israel *e-mail: aleksei.solomonov@weizmann.ac.il

Surface immobilization of oligo- and polynucleotides is ubiquitous in modern science and

technology and perpetually high scientific activity in this area stems from development of new DNA-based microarrays for biosensing, DNA diagnostics, and gene analysis as well as in drug industry.

Non-covalent immobilization of DNA on surfaces modified by polyelectrolyte multilayer (PEM)

presents a convenient and simple technique for surface functionalization. Stability of the DNA adsorbed on charged PEM depends on the length of probe. Long native DNA molecules demonstrated high stability on the surfaces and showed practically no desorption after immobilization, hybridization or after heating. However, short oligo-DNA probes commonly used in biosensing applications showed a tendency to be released into a solution impeding the use of the method in biosensing applications.

We have systematically studied adsorption and stability of DNA on PEM and developed simple

route for stabilization of functionalized interface. Single- and double-stranded DNA molecules were adsorbed on PEM of polyallylamine hydrochloride (PAH) and polystyrene sulphonate (PSS) formed on glass or metal (gold, silver) island films. Amine-terminated DNA was adsorbed on PEM with outer PAH layer following by cross-linking with glutaraldehyde and reduction with sodium cyanoborohydride. The use of HEPES buffer as solution for both accumulation of PEM and adsorption of DNA increased surface coverage and hybridization yield of immobilized DNA probe.

Labelling of oligo-DNA (23 mer) strands by chromophores allowed monitoring and quantification of

both DNA probe immobilization and binding to complementary DNA using transmission UV-vis and by fluorescence spectroscopy. For gold and silver island films accumulation of PM and oligo-DNA was followed by localized plasmon resonance spectroscopy (LSPR).

DNA probes immobilized on PEM showed high (up 1.1·1013 molecules/cm2) surface coverage. In

agreement with previous studies, we found gradual desorption of DNA during washing and hybridization/melting cycling. Cross-linked DNA-PEM layer retained high hybridization yield for complementary DNA binding is close to 100%, while surface coverage in hybridization/melting cycling remained constant. Variation of the number of PAH/PSS bilayers had no effect on the interface stability. Even single PAH-DNA bilayer showed the same specific binding of complementary DNA.

Stabilization of DNA-PM interface allowed the measurement of denaturation profiles of surface-

bound DNA for complementary and unrelated strands providing information of organization of DNA complexes. Melting temperature of double-stranded DNA linked to the surface was close to the value found in solution. Experiments with single- and double mismatch surface complexes showed systematic decrease of melting temperature. Melting temperature of preformed DNA duplex and stepwise-adsorbed surface complex does not depend on preparation route. Therefore, we assume that stepwise binding of the complementary strand to the DNA-PM interface results in the double helix formation.

The sensing capabilities of functional interface were exemplified in DNA biosensing using LSPR

transducers based on island Au films. Experiments with binding complementary and unrelated DNA strands LSPR showed robustness and selectivity of DNA-PEM interface.

We assume that robust DNA-PEM interface obtained by electrostatic adsorption following by

covalent binding of DNA probe and cross-link of the PEM will find numerous applications in biotechnology and biosensing.

#Prof. Israel Rubinstein passed away on October 21, 2017.

1

ELECTROCATALYSIS OF OXYGEN REDUCTION BY USING METALLOPORPHYRIN-GRAPHENE HYBRID FILMS

M. Eliyahu1, A. Bettelheim1 and E. Korin1

1Department of Chemical Engineering, Ben-Gurion University of the Negev

*eliyhoo@post.bgu.ac.il

The main reason of global warming is carbon dioxide and other air pollutants that are emitted as a result of using fossil fuels[1]. All these problems increase the motivation for scientists to develop clean and renewable energy sources and search for alternatives to the use of fossil fuels. Fuel cell is a device that converts chemical energy directly into electric energy with a high power density and high conversion efficiency[2]. Hydrogen fuel cells provide clean energy transportation with almost zero carbon dioxide emissions and no air pollution. Oxygen reduction reaction (ORR) occurs at the cathode of the fuel cells. This reaction is considered to be very sluggish and therefore it is a necessity to use catalysts to improve the kinetics. Electrocatalytic reduction of oxygen occurs in 2 main pathways: direct reduction of oxygen to water by a four-electron pathway and indirect reduction of oxygen by a two-electron pathway forming hydrogen peroxide as an intermediate[3]. The latter pathway is considered to be the less preferable one because it occurs at a lower potential, it offers less current density per unit area, and because the hydrogen peroxide causes degradation of the catalysts components. Cobalt-porphyrins have been extensively studied and demonstrated a good catalytic activity for ORR, but most of them show activity only for the two-electron pathway to yield H2O2[4]. The present research focuses on the electrocatalytic ORR by metalloporphyrin-graphene systems. Electrodeposition of carboxylic graphene oxide (CGO) is possible due the reduction of the oxygen groups on the surface of the graphene sheets[5]. Cobalt-tetra(N-methyl-4-pyridyl)-porphyrin (CoTMPyP) was incorporated into the graphene film during the electrodeposition process in order to obtain reduced carboxylic graphene oxide (rCGO)-CoTMPyP hybrid film. The electrostatic interactions and the π-π stacking between the aromatic rings of rCGO and CoTMPyP lead to a self-assembled structure which contributes to the incorporation of the CoTMPyP between the rCGO layers. The properties of the metalloporphyrin-graphene systems were examined by using various electrochemical and spectroscopic methods. UV/Vis spectroscopy measurements for rCGO/CoTMPyP films showed a 16 nm red shift for the CoTMPyP Soret band observed around 438 nm. It is well known that this red-shift indicates π-π stacking interactions between the rCGO and the CoTMPyP. The electrocatalytic activity was studied towards ORR in alkaline media for modified glassy carbon electrode coated with electrodeposited film of rCGO/CoTMPyP. The results showed that the O2 catalytic reduction peak was anodically shifted by 120 mV for rCGO/CoTMPyP in comparison to that observed for CoTMPyP (-0.19 and -0.31 V vs. Ag/AgCl, respectively). The rotating ring-disk electrode experiments showed high hydrogen peroxide production of ~87% for the rCGO/CoTMPyP film, which could be diminished by including a H2O2 dismutation manganese-based porphyrin. References [1] J. Polak, Advances in Fuel Cells, vol. 4. 1986.

[2] P. P. Edwards, V. L. Kuznetsov, W. I. F. David, and N. P. Brandon, “Hydrogen and fuel cells: Towards a

sustainable energy future,” Energy Policy, vol. 36, no. 12, pp. 4356–4362, 2008.

[3] L. Zhang, J. Zhang, D. P. Wilkinson, and H. Wang, “Progress in preparation of non-noble

electrocatalysts for PEM fuel cell reactions,” J. Power Sources, vol. 156, no. 2, pp. 171–182, 2006.

[4] “Electrocatalytic Reduction of Dioxygen by Cobalt,” pp. 1139–1149, 1984.

[5] L. Chen, Y. Tang, K. Wang, C. Liu, and S. Luo, “Direct electrodeposition of reduced graphene oxide on

glassy carbon electrode and its electrochemical application,” Electrochem. commun., vol. 13, no. 2, pp.

133–137, 2011.

2

THE EFFECT OF MATRIX-NANOPARTICLE INTERACTIONS ON THE RECOGNITION OF ARYLDIAZONIUM NANOPARTICLES IMPRINTED

MATRICES

L. Dery†, N. Bruchiel-Spanier†, N. Tal, S. Dery, E. Gross and D. Mandler*

Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel Linoy.aharon@mail.huji.ac.il

The selective recognition of nanoparticles (NPs) can be achieved by nanoparticles imprinted matrices (NAIMs) by which NPs are imprinted in a matrix followed by their removal to form voids that can reuptake the original NPs. The recognition depends on supramolecular interactions between the matrix and the shell of the NPs, as well as on the geometrical suitability of the imprinted voids to accommodate the NPs. In this research, gold NPs stabilized with citrate (AuNPs-cit) were pre-adsorbed onto a conductive surface followed by electrografting of p-aryldiazonium salts (ADS) with different functional groups on the non-occupied areas. The thickness of the matrix was carefully controlled by changing the number of repetitive scans using CV. The AuNPs-cit were removed by electrochemically dissolution. The recognition of the NAIMs was determined by reuptaking the original AuNPs-cit by the imprinted voids. We found that the recognition efficiency is a function of the thickness of the NAIM layer and is sensitive to the chemical structure of the matrix. we demonstrated that the reuptake of AuNPs-cit dramatically decreases when the layer is too thick due to the physical barrier of the cavities that prevents the reuptake of AuNPs-cit. On the other hand, we showed that layers with thickness of less than 3 nm allow non-specific recognition due to electron transfer from AuNPs-cit adsorption on top of the ADS matrix. Additionally, a subtle change of the functional group of p-aryldiazonium building block, which was varied from an ether to an ester, affected significantly the recognition ability of the NPs.

References: [1]. Bruchiel-Spanier, N.; Dery, L.; Tal, N.; Dery, S.; Gross, E.; Mandler, D. Nano Research 2019, 12 (2), 265-271. Acknowledgments: We would like to acknowledge the Hebrew University center for Nanoscience and Nanotechnology.

3

Electrocatalytic Reduction of CO2 and Oxidation of CO Catalyzed by

Polyoxometalates

Dima Azaiza-Dabbah and Ronny Neumann

Department of Organic Chemistry Weizmann Institute of Science, Rehovot, Israel

Email:azaiza.dima@weizmann.ac.il

It is known that the greenhouse effect is highly influenced by the concentration of CO2 in the atmosphere. The

sources of CO2 are: power generation, public electricity and heat production from fossil fuel combustion. Previous

research shows different ways to reduce CO2 emission into the atmosphere, by reduction of the amount of CO2

produced, use of CO2, and storage of CO2 1-2.

There are many organometallic complexes that can be used as catalyst for CO2 reduction but these complexes

have some disadvantages: Some transition metals are rare and expensive, part of them are not stable during the

electrocatalytic reduction reaction and the synthesis of the ligand might be complicated. In this research, we try

to reduce CO2 with other kind of structures that called polyoxometalates. Polyoxometalates are soluble, generally

anionic, metal oxide oligomers formed by oxo species of high valent transition metals (W(VI), Mo(VI), V(V)

with one or more bridging oxygen atoms. The interest in polyoxometalate chemistry is largely due to their variety

of structures, sizes, redox activity, solubility, and thermal stability. Different structures of polyoxometalates have

been described, one of them the Keggin structure [XM12O40]n. Multiple lacunary structures obtained by removal

of MO units of the Keggin structure are also known 3-6.

The main goal of the project was to first prepare as series of tri-transition metal substituted Keggin type

polyoxometalates containing Cu(II), Fe(III) and Ni(II) and combinations three of, but more importantly to appraise

the activity of these compounds as electrocatalysts for the reduction of CO2. Thus, we have found that the

trimetallo Cu(II) substituted polyoxometalate shows a catalytic peak in the presence of CO2. After 15 h of bulk

electrolysis of CO2 at -2.5 V we obtained CO selectively, with a total TON of ~4x106 and a TOF=76 s-1 calculated

relative to the surface area of the electrode and faradaic efficiency of 94%. These values are the highest values

compared to other isostructural first row transition metals polyoxometalates that we synthesized. When evaluating

the activity of the polyoxometalates based on Fe(III) and Ni(II) and combinations thereof, we observed that the

high TOF values obtained from the CV measurements were not observed in the controlled electrolysis experiments

and in some case no CO or any other reduced product was observed. Since, one of the known enzymes for CO2

reduction has a Fe-Ni active site, and this enzyme also oxidizes CO to CO2 at higher rates, we suspected that this

is also a possible explanation for the reduced formation of CO and the low faradaic efficiency in the controlled

potential electrolysis experiments.

References:

1. M. Mikkelsen, M. Jørgensen and F. C. Krebs, Energy Environ. Sci., 2010, 3, 43–81.

2. M. Cokoja, C. Bruckmeier, B. Rieger, W. A. Herrmann and F. E. Kuhn, Angew. Chem. Int. Ed, 2011,

50, 8510-8537.

3. M. T. Pope, Heteropoly and Isopoly Oxometalates, 1983, Springer-Verlag: New York.

4. L. C. W. Baker, J. S. Figgis, J. Am. Chem. Soc. 1970, 92, 3794.

5. N. H. Nsouli, A. H. Ismail, I.S. Helgadottir, M.H. Dickman, J.M. Clemente-Juan, U. Kortz, Inorg,

Chem, 48,5884, (2009).

6. E. Haviv, D. Azaiza-Dabbah, Raanan Carmieli, Liat Avram, Jan M. L. Martin, Ronny Neumann,

Journal of the American Chemical Society, 2018, 140 (39),12451-12456.

4

NI-BASED DOUBLE HYDROXIDES AS ANODE CATALYSTS FOR ELECTRO-OXIDATION OF UREA

Sankalpita Chakrabarty, David Eisenberg

Schulich faculty of chemistry Technion-Israel Institute of Technology

Sankalpita.chakrabarty@gmail.com

Urea is the most extensively used nitrogen-rich fertilizers and one of the significant chemical intermediate of pharmaceutical industry1, 2. However the production and use of urea associated with a release of urea-containing wastewater has adverse environmental effects. Urea undergoes a natural conversion to ammonia and other toxic species such as nitrates, nitrites, and NOx that release to air and groundwater which can trigger the air pollution and eutrophication of waters system3. On the other hand, the electro-oxidation of urea produces large amount of hydrogen in cathode which can be a potential source of alternative renewable energy with additional advantage of wastewater treatment4. Therefore, the electrolysis or electro-oxidation of urea has become one promising approach to overcome the environmental threat with the ability to produce hydrogen gas. Furthermore, the required theoretical potential for oxidation of urea (0.37V vs RHE) is considerably lower than the water oxidation (1.23V vs RHE) which makes it superior to hydrogen economy5. Surprisingly the urea electro oxidation does not occur effectively by noble metal catalyst whereas low cost Ni plays major role. During the elctro-oxidation of urea Ni is oxidized to NiOOH (Ni+3 State) and oxidizes urea by forming N2, CO2 and itself reduced back to Ni(OH)2 (Ni+2 state)6,7. Although pure Ni shows catalytic activity, there are still disadvantages like high onset potential, low current density and stability, which demands to find out other alternate Ni-based electrocatalyst for urea oxidation. Recently Ni based double hydroxide has drawn attention for electrochemical water splitting application8-10, but it is still unexplored in the field of urea electro-oxidation. Herein the Ni-based double hydroxides are synthesized by simple hydrolysis and precipitation method. The as prepared materials are investigated for oxidation of urea in alkaline medium. The incorporation of other metal in the Nickel hydroxide improves the kinetic of the oxidation reaction by lowering the onset potential. The increasing urea concentration leads to increase in the current density until the saturation level. The study opens up a possible qualitative analysis among various dopant metal in nickel hydroxide to the electrochemical oxidation of urea. References:

1. D.F. Lambert, J.E. Sherwood, P.S. Francis, Soil Res. 42 (2004) 709-717. 2. Ongley ED. Control of water pollution from agriculture. Food & Agriculture Org.; 1996. 3. A. Sanz-Cobena, T. H. Misselbrook, A. Arce, J.I. Mingot, J.A. Diez, A. Vallejo, Agric. Ecosyst.

Environ. 126 (2008) 243–249. 4. B. K. Boggs, R. L. King, G. G. Botte. Chem Commun. (2009) 4859-4861. 5. N. Kakati, J. Maiti, K. S. Lee, B. Viswanathan and Y. S. Yoon, Electrochim. Acta, 2017, 240,

175. 6. W. Yan, D. Wang, G.G. Botte, Appl Catal B Environ (2012) 127:221-227. 7. D.A. Daramola, D. Singh, G.G. Botte, J. Phys. Chem. A 114 (2010) 11513-11521. 8. K. Fan, H. Chen, Y. Ji, H. Huang, P. M. Claesson, Q. Daniel, B. Philippe, H. Rensmo, F. Li, Y.

Luo and L. Sun, Nat. Commun., (2016), 7, 11981. 9. S. Klaus, Y. Cai, M. W. Louie, L. Trotochaud and A. T. Bell, J. Phys. Chem. C, 2015, 119,

7243-7254. 10. C. Tang, H.-S. Wang, H.-F. Wang, Q. Zhang, G.-L. Tian, J.-Q. Nie and F. Wei, Adv. Mater.,

(2015), 27, 4516-4522.

5

DEVELOPMENT OF NOVEL POLYMER ELECTROLYTE FOR 3D PRINTED

FREE FORM-FACTOR BATTERY

A. Vinegrad1, H. Ragones1, G. Ardel1, Y. Kamir1, M. Goor1, Y. Shacham2, D. Golodnitsky1,3 1School of Chemistry, Tel Aviv University Tel Aviv Israel 6997801, 2School of Electrical Engineering, Tel Aviv University Tel Aviv Israel 6997801, 3Wolfson Applied Materials Research Center ,Tel Aviv University Tel Aviv Israel 6997801

adidinbr@gmail.com

The high areal-energy and power requirements of advanced microelectronic devices

favor the choice of a lithium-ion system, since it provides the highest energy density of available battery technologies suitable for the application. Several attempts have been made to produce

primary and secondary thin‐film batteries utilizing printing techniques. These technologies are still at an early stage, and most currently printed batteries exploit printed electrodes sandwiched

with self‐standing commercial polymer membranes, produced by conventional extrusion or papermaking techniques, followed by soaking in aqueous or non-aqueous liquid electrolytes. In this work we report the development and fabrication of a novel 3D-printed solid-state or quasi-solid electrolytes by fused filament fabrication (FFF). The electrolytes are composed primarily of polyethylene oxide (PEO) and polyethylene glycol (PEG) which are known ionic conductors, and polylactic acid (PLA) for enhanced mechanical properties and high temperature durability. The 3D printed electrolytes were characterized by means of SEM imaging, differential scanning calorimetry (DSC) and electrical impedance spectroscopy (EIS). The flexible quasi-solid-state printed electrolyte plasticized by ionic liquid exhibited an ionic conductivity of 2.8 × 10−4 S/cm at 60oC. The all-solid LiTFSI-based electrolyte was prepared by 3D FFF method, as well. These results pave the way for a fully printed battery, which enables free-form-factor geometries and is far superior in terms of safety compared to regular Li ion batteries due to the lack of use of volatile electrolytes liquids.

6

Plasma Electrochemistry In Ionic Liquids: Fabrication and Deposition of Metallic

Nanoparticles

Amir Kaplana*, Sharona Atlasa,b, Yanir Kadoshc, Yair Bochilnc, Eli Korinc and Armand Bettelheimc,

(a) Nuclear Research Center Negev (NRCN), Department of Chemical engineering, P.O. Box 9001, Beer-Sheva, 84190, ISRAEL

(b) Ben-Gurion University of the Negev, Department of Chemistry, P.O. Box 653, Beer-Sheva, 84105, ISRAEL

(c) Ben-Gurion University of the Negev, Department of Chemical Engineering, P.O. Box 653, Beer-Sheva, 84105, ISRAEL

*e-mail: (amirk@nrcn.org.il)

Metal nanoparticles have found extensive attention due to their unique electronic properties, chemical reactivity and potential applications such as: catalysis, optical, magnetic and electronic devices.

Ionic liquids are well known in today’s literature to be successfully employed for the synthesis and stabilization of metal nanoparticles without the addition of stabilizing agents. Moreover, ionic liquids have very low vapor pressures (typically 10- 9Pa at room temperature), which makes them suitable in either vacuum or atmospheric pressure experiments as fluid substrates or solvents.

Plasma electrolysis, is carried out to produce metallic, alloys or ceramic nanoparticles. Unlike conventional electrochemistry system, in plasma electrolysis system, the cathode or the anode is positioned just above the electrolyte surface, and the counter-electrode is immersed in the electrolyte. For the fabrication of metallic nanoparticles, plasma-induced cathodic discharge electrolysis technique is used. In principle, the cathode is positioned just above the electrolyte surface, and a plasma-induced stationary discharge is generated between the cathode and the electrolyte surface to allow for continuous electrolysis. The discharge is maintained by electron emission from the cathode, whereby atmospheric argon gas is partially dissociated to form condensed plasma in the gas phase. Therefore, when the metal ion source is dissolved in the ionic liquid, fine metal particles are formed on the surface of the ionic-liquid, which sizes are in the nano- up to micro-meter scale (depend on the experimental conditions). The plasma–electrolyte interface can provide a reactive region where active species are formed; further, due to the high-energy electrons in the plasma region, plasma chemistry and electrochemistry reactions occurs, which deviate from the conventional Faraday Law. Ionic liquids are well suitable electrolytes for the plasma electrochemical processes, because compared to water it is much easier to obtain stable and homogeneous plasma, due to their low vapor pressure.

In this work, we will demonstrate plasma electrochemistry capabilities to fabricate metallic copper nanoparticles using CuSO4 salt which is dissolved in1-Ethyl-3-methylimidazolium ethyl sulfate ([EMIM][EtSO4]). Glow plasma was formed in the cathode-electrolyte interface, under atmospheric pressure conditions using argon gas flow which was continuous supplied above the solution. We used a DC power source to apply 200V of potential difference, between the cathode (tungsten wire) and copper foil anode. Our visual pictures of the cell clearly show formation of particles that diffuse from the surface to the bulk electrolyte. Our current vs. time data, combined with in-situ optical emission spectroscopy, allow us to recognize a pattern of particle nucleation followed by growth of the nanoparticles in the ionic liquid bulk. Initial experiments were conducted to obtain Cu nanoparticles-coated carbon paper electrodes. We also extracted nanoparticles from the ionic liquid solution for further elemental analysis such as XRD and TEM. Since electrolysis using multi-discharge electrodes array can be achieved, it seems in the present research stage that plasma electrolysis method is suitable for the mass production of a variety of nanoparticles, whether discrete or incorporated in substrates.

7

STRUCTURE-MORPHOLOGY CORELATION IN NA3V2(PO4)2F3 FRAMEWORK: AN ADVANCED MATERIAL FOR NA-ION BATTERY CATHODE

Ayan Mukherjee1* and Malachi Noked1

Bar Ilan Institute for Nanotechnology and Advanced materials (BINA), Bar Ilan University, Ramat Gan, Israel

*e-mail: (ayan.chemical2015@gmail.com) Recently, Na-ion batteries (NIBs) are considered as a potential alternative to lithium-ion batteries (LIBs) due to the rich abundance of sodium, economic viability and ability to utilize electrolytes with limited cathodic stability. Cathode materials synthesis for reversible Na ion electrochemistry is very challenging, composition, crystal structure and morphology all have crucial effects on the electrochemical response and long term stabilities of the material. Na3V2(PO4)2F3 (NVPF) is considered as promising cathode for NIB, offering significant sodium storage capacity and high discharge voltage. In this study, NVPF has been synthesized by a facile solvothermal route using various vanadium sources and reaction time. Uniform hierarchical microspheres composed of nanoplates (NVPF-S) and a flower like morphology composed of layered architecture crystallizes in tetragonal structure (NVPF-F). The 3D framework of NVPF contains large tunnels along the preferred orientation which is composed of V2O8F3 bioctahedral and PO4 tetrahedra and sodium ions are positioned at fully occupied and partially occupied site. The structure of NVPF is very stable and offers rapid Na+ migration through the partially occupied sites. The detailed structure and morphology study provides a strategic pathway for controlling the electrochemical response towards SIB.

Reference:

http://nokedlab.com/

Fig. 1 XRD and SEM pattern

of NVPF-F and NVPF-S

Fig. 2 charge-discharge

performance of (a) NVPF-F, (b)

NVPF-S, cycling performance of

(c) NVPF-F, (d) NVPF-S

8

Electrolysis & Fuel Cell Discussions

Towards Catalysts Free of Critical Raw Material for Fuel Cells &Elecrolysers

15-18September 2019,

La Grande Motte, France

Study of Ruthenium Contamination Effect on Oxygen Reduction Activity of DMFC Cathode

T. Ripenbein,a C. Olewsky,a O. Ben Yehuda,b L. Keinan,b

M. Shviro,c D. Kaplana,b and E. Peled,a*

a School of Chemistry, Tel Aviv University, Tel Aviv, Israel, 69978 b Nuclear Research Center - Negev, Beer-Sheva, Israel, 84190

c Institute of Energy and Climate Research, IEK-3, Forschungszentrum J lich, Jülich, Germany, 52428 Corresponding author email address: peled@tauex.tau.ac.il

Direct methanol fuel cell (DMFC) technology is a promising energy source for portable, stationary and light transportation applications in the range of several watts and up to a few kW. Currently, one of the main drawbacks preventing widespread commercialization of DMFCs is their relatively short lifetime, up to a few thousands of hours at best. Usually a DMFC lifetime is not defined by a complete failure of the cell but by a slow and continuous degradation of the performance, up to the point when the delivered power is too low for the intended application. Several different degradation mechanisms contribute to this degradation [1], one of them is ruthenium contamination of the cathode catalyst [2] following ruthenium dissolution from the anode PtRu catalyst and its cross-over to the cathode [3]. The aim of our research is to quantitatively measure the effect of ruthenium contamination on the ORR performance of the cathode catalyst. For this purpose, different amounts of ruthenium (equivalent of 0.15-3 monolayers) were deposited on commercial Pt/C nanopowder to simulate ruthenium deposition on the cathode during a DMFC operation. The ruthenium-contaminated Pt/C powders were prepared using electroless polyol reduction method with methanol as the reducing agent. Johnson Matthey HiSPEC 8000 50%Pt/C was chosen to simulate a DMFC cathode catalyst. The composition, particles size and structure of these RuPt/C powders were verified by TGA, SEM-EDS, XPS, HR-TEM and STEM-EDS. Electrochemical characterization was performed with the use of cyclic-voltammetry and rotating–disk–electrode (RDE) techniques and compared to that of HiSPEC 8000. It was found that already at 0.25 equivalent monolayer of ruthenium (EDS %At Pt92Ru8, XPS %At Pt90Ru10) there is a massive, more that 25%, decrease in ORR specific activity of the commercial Pt/C catalyst. This decrease grows rapidly up to a complete inhibition of ORR at approximately 1 equivalent monolayer of ruthenium (EDS %At Pt64Ru36, XPS %At Pt50Ru50). The obtained results quantitatively show that ruthenium contamination indeed has a major role in the performance degradation of DMFCs.

REFERENCES

[1] A. Mehmood, M. A. Scibioh, J. Prabhuram, M. G. An, H.Y. Ha, Journal of Power Sources, 2015, 297,224–241 [2] L. Gancs, B. N. Hult, N. Hakim, S. Mukerjee, Electrochem. Solid-State Lett., 2007, 10, 9, B150 [3] P. Piela, C. Eickes, E. Brosha, F. Garzon, P. Zelenay, Journal of The Electrochemical Society, 2004, 151 (12), A2053–A2059

9

INFLUENCING BIOLOGICAL BEHAVIOR IN SINGLE CELLS USING ELECTRICAL SIGNALS

Daniel Kaufman1, William E. Bentley

2 and Hadar Ben-Yoav

*1,

1Nanobioelectronics Laboratory (NBEL), Department of Biomedical Engineering, Ben-Gurion

University of the Negev, Beer-Sheva, Israel 2Institute for Bioscience and Biotechnology Research and Fischell Department of Bioengineering,

University of Maryland, College Park, Maryland, USA *e-mail: benyoav@bgu.ac.il

Bioelectronic sensors and actuators are examples for the communication between electrical and

biological systems. This bi-directional communication is based on electrons transfer at the

bioelectronic interface by using electrodes. While the transfer of biological inputs to electronic outputs

(bio-sensors) has been widely studied, the opposite direction (bio-actuators) is lacking. The knowledge

about the mechanism of bio-actuators could be achieved by learning the phenomena in single cells.[1]

Here we present an electrochemical platform for bi-directional communication analysis in single

bacterial cells. The bacterial cells are genetically engineered E. coli and can be stimulated by an

electrochemical reaction at the vicinity of the cells. The electrochemical reaction triggers a redox

cascade and the expression of genes generating a fluorescent response. We show the

electrochemical characterization of a microfabricated platform comprising an array of 23

microelectrodes (25 μm in radius). Furthermore, we validate the fluorescent signal generated by a

suspension of bacterial cells in the presence of the redox mediators ferricyanide and pyocyanin by

using a fluorescent plate-reader detector and a microscope. Elucidating the relationship between

electrochemical inputs and biological outputs at the single cell level will enable to model and to control

the physiological behavior of cells and tissues with the long-term goal to control and prevent various

diseases.

Figure 1. [a] Electrochemical cell containing a microfabricated platform comprising 23 microelectrodes. [b] Cyclic voltammograms at increasing scan rates of ferricyanide solution. [c] Chronoamperometry of ferricyanide recorded by using the 23 microelectrodes. [d] Microscope image of E. coli (pTT101) fluorescent response in presence of ferricyanide and pyocyanin. [e] Fluorescence response rate for various combinations of redox mediators in the presence and the absence of the cells.

References: [1] Tschirhart, E. Kim, W. E. Bentley, “Electronic control of gene expression and cell behavior in Escherichia coli through redox signaling,” Nat. Commun., vol. 8, pp. 1–11, 2017. Acknowledgments: We thank Dr. Gad Vatine and Mr. Roman Khourin for their help with the plate reader/fluorescence detector measurements. We thank the Nano-Fabrication center in Ben-Gurion University for the preparation of the chips.

a b

d e

c

50nm

Ag/AgCl

reference

electrode

redox

solution gold electrode

micro-array

10

THE INFLUENCE OF SHELL-MATRIX ONTO NANOPARTICLES SELECTIVE RECOGNITION

Din Zelikovich1, Netta Bruchiel-Spanier, and Daniel Mandler*

Institute of Chemistry, The Hebrew University or Jerusalem, Jerusalem, 91904 Israel din1009zel@gmail.com

The selective recognition of nanoparticles (NPs) can be achieved by nanoparticle-imprinted matrices

(NAIMs), where NPs are imprinted in a matrix followed by their removal to form voids that can

reuptake the original NPs. The recognition depends on supramolecular interactions between the

matrix and the shell of the NPs.

Speciation of nanoparticles, that is, their differentiation based on size, shape and stabilizing shell, is

becoming important because properties such as toxicity are strongly depend on these parameters.

Here, gold NPs stabilized with various ligands such as citrate (AuNPs-cit) and mercapto-acetic acid

(AuNPs-maa) with the same core size were absorbed onto Pt surface followed by electrografting of

aryl diazonium salts (ADS). The thickness of the matrix was carefully controlled by changing the

number of the cyclic voltammetry cycles of the aryl diazonium reduction. The AuNPs were removed by

electrochemical dissolution. The recognition of the NAIMs was determined by the reuptake of the

original AuNPs by the imprinted voids.

11

ENZYME-BASED PHOTOELECTROCHEMICAL SYSTEMS FOR PHOTOBIOCATALYTIC PROCESSES

D. Mukha, Y. Cohen 11, O. Yehezkeli 1

1 Faculty of Biotechnology & Food Engineering, Technion, Israel dina.mukha@live.com

With increasing energy demands and rising levels of CO2, methods for alternative energy sources are being explored. Bioelectrocatalysis and photoelectrocatalysis are emerging tools for the generation of electrical power or fuels. The natural photosynthesis apparatus utilizes light irradiation for the generation of fuels. Different methods to mimic the photosynthesis process have been developed, where enzymes or inorganic semiconductors were used. While photosystem I and photosystem II have ~100% quantum efficiency, stability issues and high isolation cost limits any further photosystem-based applications. In recent years, “photosynthesis-like” photoelectrochemical cells and photobioeletrochemcial cells were developed. These cells utilize semiconductors or enzymes for the generation of electrical power or fuels. Enzymes are “super-catalysts”, enabling high selectivity, fast turnover rates, and low activation barriers, while semiconductors can harness solar energy for the generation electron flux. By exploiting the advantages of both the enzymes and the semiconductors we can further design energy generating devices. Here we present the construction of photobioelectrochemical cells which utilize bilirubin oxidase from a thermophilic Bacillus pumilus and bilirubin oxidase from Myrothecium verrucaria with superior activity and stability at elevated temperatures.1 BOD was integrated into electrodes and utilized for bioelectrocatalytic oxygen reduction process. A polymer-based BOD entrapping technique was developed and tested in a systematic work. Obtained superior bioelectrocatalytic currents and different parameters that influence the directed or mediated electron transfer process will be presented and discussed. We further present an optimized photoanode based on BiVO4, which facilitates the oxidation of water into oxygen under light irradiation. Finally, we present the construction of BiVO4/BOD bias-free, donor-free photobioelectrochemcial cells that generate electrical power at neutral pH having light irradiation as the only required input. The photobioelectrochemical cells developed enable efficient conversion of light energy to electric potential alongside with consumption of oxygen available for desired chemical transformations in situ. The different configuration and the obtained power outputs results will be discussed and analysed. References [1] BiVO4/Bilirubin Oxidase-Based Photobioelectrochemical Cell for Light-Triggered Electrical

Power Generation D. Mukha, Y. Cohen, T. Zilberfine and O. Yehezkeli, submitted, 2019

12

WATER SOFTENING USING CAPACITIVE DEIONIZATION

Eilon Miara, Zohar Sahray, Amit N. Shocron, Matthew E. Suss*

Faculty of Mechanical Engineering, Technion – Israel Institute of Technology, Haifa, Israel

*e-mail: mesuss@me.technion.ac.il Capacitive deionization (CDI) is a fast-emerging technology used for water treatment [1]. CDI cell typically consists of two or more porous electrodes, spacers and a power source with feed water flows through the cell while supplying a constant voltage or current between the electrodes. The ions are electrosorbed into the micropores (pore diameter smaller than ~2[nm]) resulting in decrease of the effluent bulk concentration. Water softening refers to the removal of hard minerals such as Calcium and Magnesium out of aqueous solutions, which can prevent them from reacting with soap anions, increasing cleaning efficiency. In our model, we took into consideration the size-based ion selectivity mechanism [2] which gives adsorption preference for small ions over larger ones. CDI cells for water softening is promising, as it consumes relatively little energy and does not require any expensive membranes, or high-pressure pumps. On the other hand, the hardness minerals are generally larger compared to the other ions in the solution; therefore, we want to test the influence of the size-based selectivity mechanism on the effectiveness of water softening using CDI. Here, we developed a mathematical model simulating water softening using CDI cells. We performed an innovative integration between several models, combining multi-ions solution [3] and ion-size based selectivity mechanism [2] with transport equation describing concentration and potential fields as a function of time. The model was solved by COMSOL Multiphysics, and its results were used to examine how size-based selectivity mechanism affects water softening by CDI cells. To deal with the case of general solution, we developed a MATLAB application which constructs a tailored COMSOL model for the specific analysed problem. In Figure 1 we present results of a COMSOL simulation using wastewater solution. We displayed the scaled effluent concentration of all ions in the solution as a function of time. We find the concentration of the Magnesium and Calcium ions decreases with time; therefore, we conclude that using CDI cells for water softening is an achievable goal.

Figure 1: Scaled effluent concentration as a function of time for five ions. Inset: cell voltage as a function of time.

References [1] Suss, M. E., Porada, S., Sun, X., Biesheuvel, P. M., Yoon, J., and Presser, V. (2015). "Water desalination via capacitive deionization: what is it and what can we expect from it?". Energy & Environmental Science, 8(8), 2296-2319. [2] Suss, M. E. (2017). "Size-Based Ion Selectivity of Micropore Electric Double Layers in Capacitive Deionization Electrodes". Journal of The Electrochemical Society, 164(9), E270-E275. [3] Biesheuvel, P. M., Fu, Y., and Bazant, M. Z. (2012). "Electrochemistry and Capacitive Charging of Porous Electrodes in Asymmetric Multicomponent Electrolytes". Russian Journal of Electrochemistry, 6, 580-592.

13

Mitigating Structural Instability of High-Energy Lithium- and Manganese-Rich LiNixMnyCoz Oxide by Interfacial Atomic Surface

Reduction

H. Sclar1, Rosy*,1,2, Eliran Evenstein1,2, Shira Haber3, Sandipan Maiti1, Tali Sharabani1,2, Michal

Leskes3, and Malachi Noked*,1,2

1Department of Chemistry, Bar-Ilan University, Ramat Gan 5290002, Israel,

2Bar-Ilan Institute of Nanotechnology and Advanced Materials, Ramat Gan 52900, Israel, 3Department of Materials and Interfaces, WIS, Rehovot 7610001, Israel.

*e-mail: rrosysharma@gmail.com; malachi.noked@biu.ac.il ABSTRACT: Surface modification of electrode materials using chemical treatments [1] and atomic layer deposition [2] is documented as an efficient method to stabilize the lattice structure as well as to reinforce the electrode/electrolyte interface. Nevertheless, expensive instrumentation and intrinsic deterioration of the material under high-temperature conditions and aggressive chemical treatments limit their practical application. Here, we report enhanced electrochemical stability and performances by simple atomic surface reduction (ASR) treatment of Li- and Mn-rich 0.35Li2MnO3·0.65LiNi0.35Mn0.45Co0.20O2 (HE-NMC). We provide mechanistic indications showing that ASR altered the electronic structure of surface Mn and Ni, leading to higher stability and reduced parasitic reactions. We demonstrate significant improvement in the battery performance with the proposed surface reduction, which is reflected by the enhanced capacity (290 mAh g−1), rate

capabilities (∼15% enhancement at rates of 1 and 2 C), 50−60 mV narrow voltage hysteresis, and faster (twice) Li+ diffusion. Utilizing online electrochemical mass spectrometry (OEMS), we show in-operando that the reduced surface layer results in suppressed side reactions. We further characterized the surface coating with high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and solid-state NMR before and after cycling. The results presented herein address all the critical challenges associated with the complex HE-NMC material and thus provide a promising research direction for choosing relevant methodology for surface treatment. References [1] Chen, Z.; Chao, D.; Lin, J.; Shen, Z. Mater. Res. Bull. 2017, 96, 491−502 [2] Zheng, J.; Gu, M.; Xiao, J.; Polzin, B. J.; Yan, P.; Chen, X.; Wang, C.; Zhang, J.-G. Chem. Mater. 2014, 26, 6320−6327 Acknowledgments: Rosy is thankful to the Planning and Budgeting Committee of the Council for Higher Education for awarding post-doctoral research fellowship. M.N. and M.L. are thankful to the Israeli Council for Higher Education for Alon fellowship. S.H. would like to acknowledge the Sustainability and Energy Research Initiative (SAERI) fellowship. The project was conducted through the support of INREP and through the support of IMOE. We thank the ISF for equipment support (M.N., grant nos. 2028/17 and 2209/17) and funding (M.L., 1580/17).

14

DETECTION OF CHIRAL MOLECULES USING ELECTROCHEMICAL METHODS O.E Maruani1,2, H. Ben-Yoav1 and A. Milo2 *

1Department of Biomedical Engineering, 2Department of Chemistry, Ben-Gurion University of the

Negev, Beer Sheba, 8410501,Israel *anatmilo@bgu.ac.il

A molecule is defined as chiral if it can exist as stereoisomers that consist of non- superimposable

mirror images. The response of an organism to a molecule often depends on the binding between the

molecule receptor site. Ideally, these chemicals should only consist of the pure active isomer. For

example, amino acids, vitamins, and hormones are naturally produced stereo specifically (affording a

specific stereoisomer). However, the separation and detection of these isomers is often the bottleneck

in the production of chiral chemicals. The detection and analysis of enantiomeric excess is currently

performed by chromatographic or electrophoresis methods, which are limited to a laboratory setting and

suffer efficiency and accuracy limitations. In this work, we present an analytical method that relies on

combining electrochemical sensing with chiral interactions, but as opposed to previous electrochemical

methods [1,2,3], the chiral interaction will not occur on a heterogeneous surface of the electrode but

rather in solution. This will enhance the strength and statistical distribution of chiral recognition events,

allowing for increased sensitivity. We selected to focus on a modular system that combines an

electrochemically active component with a molecular modifier that can bind in situ under measurement

conditions. The binding between an electrochemically active diol, namely catechol, and different phenyl

boronic acids (BAs), was exploited to fine-tune its reduction and oxidation potentials. The oxidation

potential of the catechol increased by approximately 30mV and was dependent on the nature and

location of substituents on the BAs. By expanding this methodology to chiral diols, such as L-DOPA, we

wish to construct an array of detectors that would provide a fingerprint for the detection of chiral analytes.

(Fig.1)

1. Nie, Runqiu, et al. "Chiral electrochemical sensing for tyrosine enantiomers on glassy carbon electrode

modified with cysteic acid." Electrochemistry Communications 27 (2013): 112-115.

2. Mirri, Giorgio, et al. "Electrochemical method for the determination of enantiomeric excess of binol using redox-

active boronic acids as chiral sensors." Journal of the American Chemical Society (2010): 8903-8905.

3. Arnaboldi, Serena, et al. "Inherently chiral electrodes: the tool for chiral voltammetry." Chemical science (2015):

1706-1711.

-0.2 0.0 0.2 0.4 0.6 0.8 1.0

-100

-80

-60

-40

-20

0

20

40

60

80

100

120

Cu

rre

nt

(mA

)

E vs Ag/AgCl (V)

L DOPA: L Proline 3hr

L DOPA: L Proline 4hr

L DOPA: L Proline 5hr

L DOPA: L Proline 6hr

L DOPA: L Proline 7hr

L DOPA: L Proline: BA 3hr

L DOPA: L Proline: BA 4hr

L DOPA: L Proline: BA 5hr

L DOPA: L Proline: BA 6hr

L DOPA: L Proline: BA 7hr

Figure 1cyclic voltammetry of L-DOPA, L-Proline and BA in PBS pH=3

15

3D PRINTED LAB-ON-A-CHIP FOR WHITE BLOOD CELLS DETECTION

Shani Kleiman1, Teddy Zagardan1, and Hadar Ben-Yoav1, *

1Nanobioelectronics Laboratory (NBEL), Department of Biomedical Engineering, Ben-Gurion University of the Negev, 8410501 Beer Sheva

*e-mail: benyoav@bgu.ac.il

White blood cells (WBCs) levels are an important diagnostic parameter in many diseases [1]. Analytical laboratories for WBCs counting are rarely present in developing countries, therefore, limit the outcome of disease diagnosis and treatment [1]. To overcome this fundamentally diagnostic challenge, electrochemical lab-on-a-chip micro-systems can provide the requirements for a rapid, low cost, portable, and reliable analytical test [2] to measure and count the electrochemical bio-impedance signature of WBCs. 3D printing technology has the potential to overcome the standard technique's barriers by allowing a low-cost, one-step fabrication and rapid prototyping of lab-on-a-chip micro-systems. However, there is no knowledge on the bio-impedance signal generated from WBC in those 3D printed devices, which is hypothesized to have a low single-to-noise ratio. In this project, we present the utilization of 3D printing technology to fabricate an electrochemical lab-on-a-chip and to study the bio-impedance signal generated from WBCs. By better understanding the bioelectronic WBC-electrode interface, we will improve the quality of the extracted biological information. We preformed electrochemical impedance spectroscopy measurements with a ferrocyanide/ferricyanide redox couple solution to characterize the electrode-electrolyte interface in the printed lab-on-a-chip. We observed a linear dependence of the constant phase element amplitude (negative relationship) and of the charge transfer resistance (positive relationship) on the velocity of the flow in the lab-on-a-chip’s channel (Figure 1). We tested the impedance signal generated from flowing polystyrene micro-spheres (6 and 15 µm in diameter). We measured perturbations with the total real and imaginary part of the impedance in the presence of the 15-µm spheres – perturbations that increased by approximately 100 ohms in comparison to a solution in the absence of the spheres. Moreover, duration of each perturbation was 24 seconds and was similar to the calculated time that will last for a micro-sphere to pass the electrodes (28 seconds). Furthermore, a negative relationship was observed between the perturbation duration measured with 6 µm micro-spheres and the solution velocity in the channel. By studying this signal, we can better understand the bioelectronic system (WBC-electrode interface) and to improve the quality of the information extracted from the bioimpedance with relationship to the WBCs. Such understanding will help developing 3D printed devices for WBCs counting and to promote diagnosis of different diseases in third world countries.

References: [1] X. Wang, G. Lin, G. Cui, X. Zhou, and G. L. Liu, 2017, White blood cell counting on smartphone paper electrochemical sensor, Biosensors and Bioelectronics, 90, 549–557. [2] F. Caselli, A. De Ninno, R. Reale, L. Businaro, and P. Bisegna, 2018, A novel wiring scheme for standard chips enabling high-accuracy impedance cytometry, Sensors and Actuators B: Chemical, 256, 580–589.

Figure 1-Equivalent electrical circuit's elements as a function of the velocity ratio To the left is the constant phase element amplitude (Q) and to the right is the charge transfer resistance (R).

16

COMPARISON OF THE CATALYTIC ACTIVITY OF CARBON, SPINEL-BASED,

AND CARBIDE MATERIALS IN THE SODIUM-AIR BATTERY

E. Faktorovich-Simon1, A. Natan2, E. Peled*1, D. Golodnitsky*1,3

1School of Chemistry, Tel Aviv University, Tel Aviv, Israel, 2Department of Physical Electronics, Tel Aviv University, Tel Aviv, Israel,

3Wolfson Applied Materials Research Center, Tel Aviv University, Tel Aviv, Israel *e-mail: golod@tauex.tau.ac.il, peled@tauex.tau.ac.il

Rechargeable sodium-oxygen batteries have attracted much interest in recent years, owing to their high theoretical specific energy, and the abundance of sodium. The material of which the cathode is constructed influences the performance of the battery. In this study, we show that low-surface-area glassy carbon (GC) cannot operate for more than four consecutive cycles, whereas high-surface-area carbon materials, such as Black Pearl 2000 carbon (BP 2000), significantly increase the number of cyclic- voltammetry runs, without current reduction. NiCo2O4 was previously considered a promising material for the cathode. However, its activity was not compared with the only carbon-based electrode. Here we compare the electrochemical performance of four different NixCoyOz powders to BP 2000, XC72R, and SB carbon. The highest current-density peaks of ORR and OER were obtained for the annealed Ni:Co_35:65 catalyst, indicating its enhanced performance. Although NaO2 and Na2O2 were found as the discharge products on both GC and NixCoyOz, the latter facilitates more chemical disproportionation of NaO2 to Na2O2 than does GC. Accelerated stress tests of XC72R, BP 2000, SB, and TiC powders, after 100 cyclic-voltammetry cycles, showed that the most severe degradation of the catalyst occurs during oxidation of the reduction products. Partial support for this work was obtained from the Israeli Committee for Higher Education and the Israeli Prime Minister’s Office via the INREP project.

17

METALLOPORPHYRIN-QUINONE SYSTEMS AS ELECTROCATALYSTS FOR THE HYDROGEN EVOLUTION REACTION

Lior Ezuz, E. Korin and A. Bettelheim

Chemical Engineering department, Ben-Gurion University of the Negev,

liorez@post.bgu.ac.il Climate changes due to emission of greenhouse gases upon uncontrolled burning of fossil fuels and rapidly growing global energy demands are driving the development of alternative, renewable, and sustainable energy sources. [1] Hydrogen has been considered as an ideal and environment-friendly fuel due to its high energy density and its sole combustion product being water. The most effective hydrogen evolution reaction (HER) catalysts are Pt-group metals with a low overpotential to generate large cathodic current densities. However, the high cost and scarcity severely limit their broad utilization. [2] These

considerations have spawned efforts to design catalysts based on earth abundant transition metals. This research examines the H+/H2 redox couple by using metalloporphyrins which some of them have been reported to be highly active for HER. We exploit the unique mechanism of quinine based proton coupled electron transfer [3] to improve the catalytic efficiency toward HER of mettaloporphyrin-quinone systems. The structure of the catalysts (quinones and porphyrins) was characterized by UV-VIS spectra, FTIR, XPS and Raman analysis. The results showed that there is an effect of the metal ion in the porphyrin, cobalt being the most effective toward HER with high current density 11 mA/cm2 and onset potential of -0.65 V vs Ag/AgCl. Additionally, there is an effect of electron donating/withdrawing substituents. High donating substituents on the catalyst improve the performance and the current density obtained with a tetra amino quinone catalyst is 45 mA/cm2 with an onset potential of -0.8 V vs Ag/AgCl. The highest electrocatalytic activity towards HER was obtained by a large π-conjugated system consisting of a quinone and cobalt porphyrin (current density of 32 mA/cm2 at a potential of -0.65 V vs. Ag/AgCl). References [1] Beyene, B. B., Mane, S. B., & Hung, C. H. (2015). Highly efficient electrocatalytic hydrogen evolution from neutral aqueous solution by a water-soluble anionic cobalt (II) porphyrin. Chemical Communications, 51(81), 15067-15070. [2] Zhou, W., Jia, J., Lu, J., Yang, L., Hou, D., Li, G., & Chen, S. (2016). Recent developments of carbon-based electrocatalysts for hydrogen evolution reaction. Nano Energy, 28, 29-43. [3] Son, E. J., Kim, J. H., Kim, K., & Park, C. B. (2016). Quinone and its derivatives for energy harvesting and storage materials. Journal of Materials Chemistry A, 4(29), 11179-11202.

18

Lithium Isotope Separation by Combining Ion Exchange and Electrochemical Amalgam

Methods

Pavel Kudryavtsev

Professor, Deputy Director for Research and Development, Polymate Ltd - Israeli Nanotechnology Research Center,

POBox 73, Migdal HaEmek 2310001, Israel,

E-mail: pgkudr89@gmail.com

Natural lithium consists of two stable isotopes: 6Li (7.5%) and 7Li (92.5%). The 6Li and 7Li isotopes have different

valuable nuclear properties, for example, they have different cross-sections for the absorption of thermal neutrons

and, accordingly, different areas of their application. 6Li is used in thermonuclear energy. 7Li is used in nuclear

reactors using reactions involving ordinary heavy elements. A more complete analysis of the applications of lithium

isotopes is given in our review. [1].

The basis of the widely used method of industrial separation of lithium isotopes is the reaction of isotope exchange

between solutions of lithium compounds and lithium mercury amalgam. The method has a number of disadvantages.

We have developed a number of highly selective inorganic ion-exchange sorbents to lithium [2,3]. As is known,

depending on the number of nucleons in the nucleus of an atom, the state of the outer electron shells of atoms

changes and subtle effects are observed, such as isotopic shift, chemical shift, and so on. In this regard, it was to be

expected that during ion exchange on ion-sieve inorganic ion exchangers, their greater affinity for 6Li isotopes may

be observed, due to its smaller size than 7Li. We found that the isotope separation factor on these sorbents can reach

α=1.027. It is known that the classical amalgam method for the separation of lithium isotopes has a separation factor

α=1,049÷1,064.

In connection with this, we developed a complex method for the separation of lithium isotopes. The proposed

method consists of combining the methods of ion exchange and the electrochemical reduction of lithium from a

solution of lithium compounds on an electrolyzer with a mercury cathode. In this case, the isotope exchange of

lithium amalgam with a solution of lithium compound occurred during electrolysis, and additional amalgam

enrichment was observed with the 6Li isotope. To further enhance this effect, an ion-exchange membrane separating

the mercury cathode from the anode space is used.

The combination of these methods allows in the future reducing the size of the cascades of separation plants and

reducing energy consumption for the implementation of this process. So the process of ion exchange practically does

not have large energy consumption. They are limited only by pumping the solution through a column with an ion

exchanger, and these processes proceed quickly.

Preliminary calculations showed that in the separation of lithium isotopes only using our proposed modification of

the amalgam process, a cascade of 170 separation plants is required when the enrichment rate for the 6Li isotope for

99.9% is reached. At the same time, for enrichment in the 7Li isotope, only 80 cascade elements are required. These

two cascades should work in parallel, transferring the lean concentrates from one cascade to the head of the other

cascade. The cascades of ion-exchange separation are established in the initial stage of the process and provide

preliminary enrichment in the 7Li isotope to 95-97%, and in the 6Li isotope to 40-50%. For this, the 7Li isotope will

require from 17 to 36 elements of the cascade, and the 6Li isotope will require from 79 to 95 elements of the cascade,

respectively. Due to the higher rate of ion-exchange processes, these stages will pass quickly enough. In addition, the

cost and cost of operating the ion-exchange elements of the cascade are much lower than the electrochemical

amalgam block. At the same time, the processes of electrochemical and amalgam enrichment will take place more

efficiently, in connection with the receipt of a pre-enriched raw material into the head of a cascade.

As a result of the process, 6LiOH and 7LiOH solutions will be obtained, which are the final products.

References

[1] Kudryavtsev P.G. Lithium In Nature, Application, Methods of Extraction (Review), Journal "Scientific Israel-

Technological Advantages", Vol.18, № 3, 2016, pp.63-83, ISSN: 1565-1532

[2] Kudryavtsev P. Kudryavtsev N. Methods for extraction of lithium from natural raw materials. Journal “Scientific

Israel- Technological Advantages", Vol.19, № 4, 2017, pp.13-36, ISSN: 1565-1535

[3] Kudryavtsev P. Kudryavtsev N. Associated petroleum waters, as a promising source of lithium. International

Journal of Petrochemical Science & Engineering, 2018, Vol. 3, No. 4, pp. 144-150

19

DESIGN, FABRICATION, AND CHARACTERIZATION OF AN INTELLIGENT ARRAY OF MICROELECTRODES FOR SCHIZOPHRENIA TREATMENT MONITORING

Matan Aroosh1, Yuly Bersudsky2, and Hadar Ben-Yoav1,*

1Nanobioelectronics Laboratory (NBEL), Department of Biomedical Engineering, Ben-Gurion University of the Negev, 8410501 Beer Sheva

2Department of Psychiatry, Beer-Sheva Mental Health Center, 8461144 Beer Sheva *e-mail: benyoav@bgu.ac.il

Schizophrenia is a chronic mental disorder that affects about 23 million people worldwide [1]. Clozapine (CLZ) is the most effective antipsychotic medication available for treatment-resistant schizophrenia patients, yet, it is dramatically underutilized due to unavailable objective tests to measure the efficacy of the treatment [2]. Various redox-active molecules in blood (e.g., Homovanillic acid [HVA]) have been shown to relate to CLZ treatment efficacy [3]. Yet, the ability to utilize electrochemical sensors to rapidly quantify HVA levels in blood is dramatically impeded due to interfering electrochemical signals measured from the sample attributed to other redox molecules. Here, we aim to develop a novel electrochemical micro-sensor to rapidly quantify HVA in blood samples of CLZ-treated schizophrenia patients. Specifically, we develop an array of microelectrodes (Fig. 1A) modified with the bio-polymer chitosan encapsulating carbon nano-tubes (chitosan-CNT) [4]. The modified microelectrodes generate a set of complex electrochemical signals from the sample that are analyzed using intelligent chemometric models. We present the successful microfabrication of an array of 24 microelectrodes using photolithography and thin film deposition techniques. The chitosan-CNT film electrodeposition process onto the microelectrodes was optimized by varying the applied anodic current and measuring the resulted film thickness. The optimization showed a positive linear relationship with an electrodeposition rate of 750 nm/sec (Fig. 1B). The electrochemical activity of the chitosan-CNT modified microelectrode was tested with a 5 mM ferrocyanide\ferricyanide redox couple solution (Fig. 1C). Cyclic voltammograms showed increased current peak values for the microelectrodes modified with 0.3 µA (11.2-times higher than bare) and 1 µA (36.8-times higher than bare) electrodeposition current densities. We tested the electrochemical activity of HVA with the modified microelectrodes and showed a positive relationship between the current peaks at the expected two oxidation (-0.03V and 0.2V vs Ag/AgCl) and reduction (0.1V and -0.1V vs Ag/AgCl) peaks and HVA concentration (Fig. 1D). The developed electrochemical micro-sensors will establish a new detection approach for CLZ treatment efficacy and will help transform schizophrenia management.

Figure 1: (A)An optical image of the electrochemical array of bare and chitosan-CNT -modified microelectrodes. (B) A linear relationship between the chitosan-CNT film thickness and the applied electrodeposition current. (C) Cyclic voltammograms recorded from a 5 mM ferrocyanide\Ferricyanide solution with either a bare (green and blue), a 300 nA -chitosan-CNT modified (black), and a 1000 nA -chitosan-CNT modified (red) microelectrodes. (D) Cyclic voltammograms recorded from 0.1 (red), 0.5 (black), and 1 (green) mM HVA concentrations with the 300 nA -chitosan-CNT modified microelectrode. References:

[1] World Health Organization, "Fact Sheets-Schizophrenia," 9 April 2018. URL . [Accessed 18 July 2019] [2] Shukla at el., 2019, Chitosan–Carbon Nanotube-Modified Microelectrode for In Situ Detection of Blood Levels of the Antipsychotic Clozapine in a Finger-Pricked Sample Volume, Advanced Healthcare Materials, 9, 1 -14. [3] Samanite at el., 2019, Biological Predictors of Clozapine Response: A Systematic Review, Frontiers in Psychiatry,9,327-356. [4] Kim at el., 2005, Chitosan to Connect Biology to Electronics, Polymers, 7(19), 1-49.

Acknowledgments: The author thanks the Nano-Fabrication Center at Ben-Gurion University of the Negev for the help microfabricating the

microelectrodes array.

A B

C D

20

NOVEL LAGP−PEI COMPOSITE ELECTROLYTE M. Lifshitz1, A. Greenbaum (Gutina)2, Y.Feldman2, S. Greenbaum3 and D. Golodnitsky1,4

1School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel 2Department of Applied Physics, Hebrew University, Jerusalem, 91904, Israel

3Physics and Astronomy Department, Hunter College, NY, US 4Applied Materials Research Center, Tel Aviv University, Tel Aviv 6997801, Israel

Email: moranl@mail.tau.ac.il; golod@tauex.tau.ac.il

Solid electrolytes (SE) have major advantages as an alternative to liquid electrolytes, in terms of reliability, safety, and easy design. SEs are generally defined as electronically insulating solid materials with high mobility and selective transport of charged ionic species within their structure. In general, they can be divided into two main categories: polymeric and inorganic. In this study we focus on the development of a novel composite Li1.5Al0.5Ge1.5(PO4)3 – Polyethyleneimine (LAGP−PEI) polymer-in-ceramic electrolyte, which contains high concentrations of ionic charge carriers with a minimal polymer concentration. Commercial nanoparticles of lithium aluminum germanium phosphate (Li1.5Al0.5Ge1.5(PO4)3, LAGP) were used as a ceramic matrix. Polyethyleneimine (PEI) was tested as a binder and lithium-ion-conducting medium. The combination of nanosize LAGP glass ceramics and PEI polymer was chosen to provide mechanical flexibility with the benefit of the high ionic conductivity of LAGP. The composite electrolytes were prepared by electrophoretic deposition (EPD). TGA, DSC, XRD, ESEM, NMR and EIS tests were used for the characterization of the samples. The dielectric properties of pristine LAGP and LAGP-based quasi-solid electrolytes, containing different concentrations of LiTFSI-based Pyr14 ionic liquid ions, were studied with the use of the BDS 80 (NOVOCONTROL) with automatic temperature control by a QUATRO Cryosystem. The complex, non-Debye dielectric response of the composite electrolyte has been described in terms of several distributed relaxation processes separated by different frequency and temperature ranges. While at low temperatures, the main contribution is from LAGP, at the middle- and high-temperature regions, the superposition of a few non-Arrhenius processes is

observed. 7Li diffusion of the composite electrolyte measured by NMR at 90C was about 6±2 E-11 m2/s. The correlation of ion-transport phenomena with XRD, DSC and ESEM data will be presented in detail. Acknowledgements The research was funded by the Israel Ministry of Science and Technology, grant 53886 and by the Israel Science Foundation (INREP project).

21

Lung-Inspired Catalyst Layers: Understanding Pore Accessibility in Hierarchically Porous Carbon

Electrocatalysts

Eliyahu Farber, Prof. David Eisenberg

Shulich Faculty of Chemistry, 604, Technion eliyahufarber@gmail.com

Hierarchically porous carbons are at the cutting edge of materials for electrochemical devices. The porous structure enables flow inside the material, while graphitic regions provide conductivity and dopants create catalytic sites. Hierarchically porous carbons have high specific surface area, exposing many active sites and improving mass transport to these sites. Nevertheless, such carbons are limited by low volumetric current densities – making typical electrodes thick, and blocking access to some of the inner surface area. We hypothesize that there exists a better type of porosity, than a random mixture of small and large pores – namely, a lung-structured catalyst layer. This requires that pores are interconnected and aligned, directing the reactant smoothly from larger pores into smaller pores and utilizing the entire surface area. We studied a range of templated carbons, aiming to elucidate the role of intra- and inter-particle porosity in lung-inspired catalyst layers. We use ZnO rods and trees, spanning 10– 1000 nm in length, to investigate the effect of flow channels and of particle dimensions on the flow in catalyst layers. By using the oxygen reduction reaction (ORR) as a model reaction, we were able to demonstrate the effect of active site accessibility on electrocatalytic performance, and to correlate it to other physical characterizations of the material.

22

FTO DARKENING RATE AS A QUALITATIVE, HIGH-THROUGHPUT MAPPING METHOD FOR SCREENING LI-IONIC CONDUCTION IN THIN SOLID

ELECTROLYTES

Shay Tirosh1,*, Niv Aloni2,**, Simcha Meir1, David Cahen1, and Diana Golodnitsky2

1 Department of Chemistry, Center for Nanotechnology and Advanced Materials, Bar Ilan University,

Ramat Gan, Israel, 529000, 2 School of Chemistry, Tel Aviv University, Tel Aviv, Israel, 69978.

*stirosh1@gmail.com, ** nivaloni10@gmail.com

High-throughput combinatorial screening of thin metal oxide films as Li-ion conductors requires a fast and easy way to evaluate the Li-ion conduction within the film. A fast qualitative indicator can be a map of Li-ion conductivity of different parts in a given film. Here we report on a new opto-electrochemical qualitative method, FTO darkening, that uses color change of the FTO substrate, onto which the investigated film was deposited. The rate of color change of the substrate reflects the rate of Li-ion conduction through the deposited film. Identification of solely Li-conduction sites has been done by comparing darkening rate of tested film with darkening rate of bare FTO and using color formation due to Ferrocene reduction as internal prob. In this work we confirm the validity of this method by testing model systems of layers containing LinLamSO4 and LixLayPO4 ceramics of different film thickness (uniform composition) and different relative composition, respectively. The darkening-rate measured by optical transmission show linear correlation with film thickness. Darkening-rate map that compared, with the resistance map, obtained by impedance measurement show successful identification of solely Li-conduction sites. Our next step is to show directly, the correlation between FTO darkening and Li-ions conductivity obtained by impedance. This research is funded by the Israel National Research Centre for Electrochemical Propulsion (INREP).

23

NEUROTRANSMITTER DOPAMINE FOULING OF GOLD ELECTRODE

Teddy Zagardan1, Nathalia Peixoto2 and Hadar Ben-Yoav* 1

1Nanobioelectronics Laboratory (NBEL), Department of Biomedical Engineering, Ben-Gurion University of the Negev, 8410501 Beer Sheva

*e-mail: benyoav@bgu.ac.il 2Electrical and Computer Engineering Department, George Mason University, Fairfax, 22030 VA,

United Stated In vivo detection of neurotransmitter (NT) dopamine is important to the diagnosis and treatment of neurodegenerative diseases such as Parkinson's disease. Current dopamine detection methods lack the required sensitivity for real time detection in biofluids due to fouling effects[1]. Here we characterize the electrochemical fouling of dopamine on gold electrodes. The fouling effect of dopamine was characterized by recording multiple cyclic voltammograms of four freshly prepared 5 mM dopamine solutions. In figure 1, a fouling effect of a commercial gold electrode can be seen by the decrease of current both in successive sweeps and between solutions originated in the same bulk solutions. The

following equation can be used to quantify the surface coverage: Γ = 𝐼𝑝4𝑅𝑇

𝑛2𝐹2𝐴𝜐 where 𝐼𝑝 is the peak

current, R is the ideal gas constant, T is the temperature, n is the number of electrons being reduced\oxidized, F is the faraday constant, A is the surface area and 𝜐 is the scan rate [2]. In figure 2 the surface coverage Γ is shown in percentage in relative to the first cycle, in the presence of 5 mM Dopamine and a control group of 5 mM ferro\ferri. As expected, the percentage of adsorbed molecules decreases due to the already fouled surface. In order to utilize in vivo NT detection by electrochemical means, the fouling effect should be studied and new methods like machine learning or by incorporating new materials with less affinity to fouling effects such as carbon based electrodes.

References: [1] J. A. Ribeiro, P. M. V. Fernandes, C. M. Pereira, and F. Silva, “Electrochemical sensors and

biosensors for determination of catecholamine neurotransmitters: A review,” Talanta, vol. 160, pp. 653–679, 2016.

[2] M. I. Prodromidis, A. B. Flown, S. M. Tzouwara-Karayanni, and M. I. Karayannis, “The importance of surface coverage in the electrochemical study of chemically modified electrodes,” Electroanalysis, vol. 12, no. 18, pp. 1498–1501, 2000.

Acknowledgments:

The author thanks IIse Katz Institute for Nanoscale Science and Technology at Ben‐Gurion University of the Negev, for their help in microelectrode microfabrication.

Figure 1: Cyclic voltammograms of DA with commercial gold electrode. 11 cycles were

conducted for each solution without cleaning between the solutions.

Figure 2: Adsorption Percentage of 5[mM] dopamine (blue) and 5[mM] (orange) on

commercial gold electrode.

24

REVEALING STRUCTURE–ACTIVITY LINKS IN HYDRAZINE OXIDATION: DOPING AND NANOSTRUCTURE IN CARBIDE–CARBON

ELECTROCATALYSTS T. Y. Burshtein 1, E. M. Farber1, K. Ojha2, D. Eisenberg1*

1Schulich Faculty of Chemistry, The Grand Technion Energy Program Technion – Israel

Institute of Technology Technion City, Haifa 3200003, Israel, 2Van ’t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, Amsterdam, 1098XH, The Netherlands.

*eisenberg@technion.ac.il The oxidation of hydrazine (N2H4) is an important challenge in electrocatalysis, with applications in direct hydrazine fuel cells and in medical and environmental sensing. Interest in alternative, nitrogen-based fuels for fuel cells was rekindled by recent advances in alkaline membranes, and by the surfacing of challenges in the transportation of hydrogen. Direct hydrazine fuel cells promise high theoretical voltage (1.56 V with O2), clean emissions, and improved fuel transportability. We now report a multi-doped carbide–carbon composite with excellent hydrazine electro-oxidation (HzOR) activity in alkaline pH (Figure 1). While iron carbide containing materials are well known catalysts for several applications (e.g. oxygen reduction and Li-ion batteries), our N-doped, Fe3C-embedded carbons provide the first examples of a carbide-based HzOR catalyst. Multi-doping was thought to enhance reactivity (possibly through cooperation of M=Cu/ Zn, Fe, and edge N atoms), possibly by pore-etching, layers exfoliation or graphitization promotion, thus modulating surface area, mass transfer and conductivity. To prepare the composites, an organometallic structure combining iron with either (1) copper, an element active towards the HzOR, (2) zinc, an electrocatalytically-inert element capable of efficient micropore etching, or (3) iron, to investigate the effect of molybdenum-doping reported earlier. Pyrolysis and washing of the fore mentioned precursors yielded HzOR-active composites of Fe3C nanoparticles and a hierarchically porous, partially graphitic N-doped carbon (NC). Thorough characterization revealed that the activity is ordered as: Cu-derived NC > Zn-derived NC > Fe-derived NC. While the catalysts had similar compositions, their nanostructure varied: both Zn- and Cu-doping induced the formation of micropores and small mesopores (5–13 nm diameter). The dopant-induced active site exposure (affecting micropore volume) and improved material flow (linked to mesopore volume) contributed to enhanced HzOR electroactivity. Furthermore, the intimate mixing of the metals in the precursor is hypothesized to homogenize and enhance the doping effect, as the structure enhancing metal ions (Zn2+ or Cu2+) exposed the nearby catalytic Fe3C sites. Acid washing of the pyrolyzed carbon was crucial for producing microporosity in the Cu-based carbon but had little effect on the Zn-derived one. This revealed the importance of micropores and small mesopores for HzOR electrocatalysis, and the different nanostructuring mechanisms of the two dopants: while Zn(g) boils during pyrolysis and thus etches micropores into the carbon, Cu(s) diffuses and spreads throughout, making exfoliation by acid reaction more efficient. [1] Burshtein TY, Farber EM, Ojha K, Eisenberg D. Revealing structure–activity links in hydrazine oxidation: doping and nanostructure in carbide–carbon electrocatalysts. Journal of Materials Chemistry A. 2019.

Figure 1. Cyclic voltammetry of average HzOR. 10 mV s−1, 1 M KOH, 20 mM hydrazine.

25

UNBIASED PHOTOELECTROCHEMICAL CELL BASED ON BIVO4/Mn12O12(O2CR)16(H2O)4 PHOTOANODE AND BILIRUBIN OXIDASE

BIOCATHODE

Y. Cohen1, N. Gluz2, L. Kolik Shmuel1, S. Bamany1, G. Maayan2, O. Yehezkeli1

1Faculty of Biotechnology & Food Engineering, Technion, Israel , 1Faculty of Chemistry, Technion, Israel

y.omer@bfe.technion.ac.il Researchers have been searching for ways to minimize the use of fossil fuels as well as alternative routes for the generation of fuels or electrical energy. In nature, Photosystem II protein enables the conversion of light energy into electron flux, while oxidizing H2O into O2. The Oxygen-evolving center consists of Mn4Ca cluster enables the challenging oxidation process, therefore, methods to mimic the natural cluster and to photoactivate it are especially attractive. Photobiofuel cells (PBFCs) are photo-electrochemical cells that utilize enzymes or proteins as catalysts for electrochemical cell activation. Here we present new methods to synthesize Mn-based clusters coupled to electrodes and further on BiVO4. Bilirubin oxidase, a copper-based metalo-enzyme can reduce oxygen into water while oxidizing bilirubin at natural pH. The protein is ideal for biotechnological applications as its copper active site accepts an electron from aromatic moieties, and therefore, allows continuous recycling of atmospheric oxygen. By coupling of the constructed biocathodes with a BiVO4 based photoanode, electrical power can be generated, while O2/H2O are being recycled at the cathode and anode, respectively. Our preliminary results indicated that ITO modification with Mn-based clusters co-catalysts enabled water oxidation catalytic reaction. The water oxidation catalytic reaction was improved with the increase of Mn-clusters layers.

MnBz

Nature Catalysis 1 (1), 48, 2018

3,4-diaminobenzoic acid

26

AGRICULTURAL DESALINATION USING CAPACITIVE DEIONIZATION

Zohar Sahray, Eilon Miara, Amit N. Shocron, Matthew E. Suss*

Faculty of Mechanical Engineering, Technion – Israel Institute of Technology, Haifa, Israel *e-mail: mesuss@me.technion.ac.il

Capacitive deionization (CDI) is a fast-emerging technology, commonly applied to brackish water desalination [1]. There are different types of CDI cells, most of which use two porous electrodes, a spacer and a power source, where the solution flows either between or through the electrodes. While supplying a constant current [2] or voltage to the cell, ions are adsorbed into the micropores (pore diameter smaller than ~2 nm) of the two electrically charged electrodes. Generally, for desalination of brackish water for agricultural uses, there is a need to remove the monovalent ions, such as Sodium and Chloride and keep the divalent ions, such as Calcium and Magnesium, in the bulk solution in order to maintain soil health. Ensuring that only the monovalent ions are adsorbed into the micropores is difficult, as typically CDI electrodes prefer divalent ions over monovalent. We want to test if techniques such as surface functionalization of the electrodes can make such a selective desalination process possible [3]. To investigate this application, we choose to model the CDI cells by one dimensional transport equations to solve for the ionic species’ concentration, the electric potential, and the potential drop across the micropore, from electrode to macropore. We developed a model including constant current operation [2] and chemical-treated electrodes [3] for multiple ion solutions. Figure 1 below presents the scaled effluent concentration as a function of time while applying constant current and account for chemical treated electrodes for the case of aqueous sodium-chloride solution. The inset presents the voltage developed in the cell as a function of time of the same system. We learn that chemical treatment can increase the desalination rate and while decreasing the voltage rise rate. We use this model for studying the influence of different selectivity mechanisms, to find suitable operation parameters for agricultural desalination by CDI.

Figure 1: Scaled effluent concentration as a function of time for three different chemical treatments while the cell operates under constant current. Inset: cell voltage as a function of time for three different chemical treatments while the cell operates under constant current.

References [1] Suss, M. E., Porada, S., Sun, X., Biesheuvel, P. M., Yoon, J., and Presser, V. (2015). “Water desalination via capacitive deionization: what is it and what can we expect from it?”. Energy & Environmental Science, 8(8), 2296-2319. [2] Yatian Qu, Patrick G. Gampbell, Ali Hemmatifar, Jennifer M. Knipe, Colin K. Loeb, John J. Reidy, Mckenzie A. Hubert, Michael Stadermann, and Juan G. Santiago (2018). “Charging and Transport Dynamics of a Flow-Through Electrode Capacitive Deionization System”. J. Phys. Chem. B 2018, 122, 240-24 [3] PM. Biesheuvel, H.V.M Hamelers, M.E. Suss (2016). “Theory of Water Desalination by Porous Electrodes with Immobile Chemical Charge”. Colloids and Interface Science Communications 9 (2015) 1-5

27

ENHANCING ENERGY HARVESTING WITH DPN-FABRICATED META-CHEMICAL SURFACES

Zorik Shamish1,2, Moshe Zohar3, Dror Shamir1, Ariela Burg*2

1 Nuclear Research Center, Negev, P.O.B. 9001, Be'er-Sheva, Israel, 2 Department of Chemical Engineering, Sami Shamoon College of Engineering, Be'er-Sheva, Israel

3 Department of Electrical and Electronics Engineering, Sami Shamoon College of Engineering, Be'er-Sheva, Israel

*e-mail: arielab@sce.ac.il Exponential growth in world population and predicted impending global energy shortages have motivated myriad studies aimed at developing alternative energy sources. Whereas the most economical usable sources of energy are coal and natural gas, they are not readily available or environmentally friendly. The current study presents an innovative method for fabrication of electrodes by Dip pen nanolithography (DPN), which could dramatically improve one of the alternative energy sources, hydrogen production. DPN is a state-of-the-art method for the production of environmentally friendly chemical surfaces, termed meta-chemical surfaces (MCS), which are analogous to meta-surfaces but show chemical features, and not optical features. As a model reaction for testing the activity of MCSs, we chose to use the oxygen-evolution reaction (OER), which constitutes a step in the water splitting process (WSP) for hydrogen formation. MCS was produced from Ni(OH)2 clusters, which are known as good catalysts for OER, which were patterned on an Indium tin oxide (ITO) surface (MCSNi). This MCS is used as an electrode for heterogeneous OER. The results show that our easy and innovative method enables the generation of efficient catalytic surfaces. Such surfaces allow control over the nano-cluster size and the distance between the clusters. These features are known to be important for selective and efficient catalysis processes, especially processes that occur at the edges of the clusters, such as OER by Ni(OH)2, and have relation between the clusters during the process like Ni(OH)2 clusters. Our results shed new light, and provide valuable insight into fabrication methods of alternative energy devices. Not only will this work afford important advances in the field of WSP-based alternative energy technology, but, ultimately, it could lead to significant breakthroughs in our ability to effectively address the global energy shortage.

28

CARBON NANOTUBES MEMBRANE FLOW-THROUGH ELECTRODE FOR THE DETECTION OF ORGANIC AND INORGANIC POLLUTANTS IN WATER

Andrea Buffa1 and Daniel Mandler*2

1,2The Institute of Chemistry, The Hebrew University of Jerusalem, 9190401 Israel

*e-mail: Daniel.mandler@mail.huji.ac.il In 2015, more than 800 million people did not have access to safe and contaminant free drinking water. Water from wells and springs can be contaminated by a variety of organic and inorganic pollutants coming from anthropogenic and natural sources such as arsenic containing rocks. Yet, also apparently safe tap water can hide threats since it can be polluted accidentally or on purpose along the supply chain. Even improper plumbing in old buildings can release poisonous heavy metals into drinking water. The major barrier that prevents careful water control is the lack of an inexpensive and simple in-situ analytical system that warns against major contaminants. The development of an easy to use and accessible (also to undeveloped countries) analytical method is still a challenge in analytical chemistry. We aim at contributing to accomplish this goal by developing a carbon nanotubes (CNT) electrochemical filter membrane able to detect ppb levels of both organic and inorganic pollutants. The high sensitivity of the method is achieved by pumping the water sample through the CNT membrane electrode, which accumulates the pollutants to be detected in a short time. The cost efficiency derives from using a simple syringe filter holder for building the electrochemical flow system. With this system, we detected 64 ppt of copper by anodic stripping voltammetry as a model system for heavy metals. Due to the adsorptive properties of CNTs, the CNT electrode is basically a fixed bed adsorption system able to detect organic contaminants by adsorptive stripping voltammetry. Organic contaminants such as tartrazine, parathion and diquat were determined in ppb levels by adsorptive stripping voltammetry by a simple and time efficient procedure. Moreover, modification of the CNT membrane by electrodeposition of gold nanoparticles enabled the application of the flow system for the detection of arsenic (III) in water with a linear range from 0.75 to 750 ppb by anodic stripping voltammetry.

Complete electrochemical flow system.

29

ELECTROCHEMICAL SENSOR FOR BLADDER CANCER DETECTION

Anat Friedman1, Rajendra Prasad Shukla1, Remi Cazelles1, Stav Biton1, Avia Lavon1, Assaf Bar El2, Gal Markel2, and Hadar Ben-Yoav1,*

1Nanobioelectronics Laboratory (NBEL), Department of Biomedical Engineering, Ben-Gurion University of the Negev, 8410501 Beer Sheva, Israel.

2The Ella Lemelbaum Institute for Immuno-oncology, Sheba Medical Center, Ramat-Gan 526260, Israel; Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv

University, Tel-Aviv, Israel. *e-mail: benyoav@bgu.ac.il

We present a novel electrochemical biosensor for early diagnosis of bladder cancer (BC). Our approach focuses on analyzing the metabolic condition oxidative stress – a specific condition that is derived by the imbalance between antioxidant and reactive oxygen species, and is related to many diseases, such as osteoarthritis [1] and BC [2]. We hypothesize to identify unique redox fingerprints of BC in urine samples of patients by recording them with an array of electrodes and analyzing the signals with chemometrics. Therefore, we modified the electrodes with reduced graphene oxide, chitosan, platinum black and carbon nanotubes (CNT)-encapsulated in chitosan bio-composite. The different modifications, which were selectively electrodeposited onto the electrodes, induced a variable set of physicochemical interactions at the electrochemical interface. These interactions influenced the diffusion and the electron transfer rate coefficients of the redox molecules in the urine. Cyclic voltammetry (Fig. 1) was used to record the electrochemical currents generated from the redox-active molecules Trolox (total antioxidant capacity marker) and hydrogen peroxide (total oxidant status marker). The anodic current peak was positively correlated to the redox molecules’ concentration. The detection performance of the redox molecules was evaluated by calculating the limit-of-detection (LOD) and the sensitivity. Platinum black and CNT demonstrated improved detection of hydrogen peroxide (LOD of 0.045 ± 0.004 mM and 0.05 ± 0.001 mM, and sensitivity of 4.63 ± 0.33 mA/M and 4.28 ± 0.15 mA/M, respectively). Furthermore, all the tested electrodes were sensitive to Trolox.

Figure. 1. Electrochemical signals measured for 0.125, 0.25, 0.5, 1, 2, and 4 mM of hydrogen peroxide and Trolox by using platinum black (A&D), bare (B&E), and chitosan (C&F) electrodes.

References:

[1] Ozcan Erel, 2005, Clinical Biochemistry, 38, 1103-1111. [2] Antioxidants in Food, Vitamins and Supplements, Editors: Amitava Dasgupta and Kimberly Klein, 1st edition, 2014, Elsevier.

Acknowledgment:

This study is funded by the Israel Cancer Association.

30

Fabrication and Evaluation of a Micro-sensor Array Chip for Personalized Medicine of Sickle Cell Disease

Remi CAZELLES,1 Rajendra PRASAD SHUKLA,1 Alexander VINKS,2 Russel WARE,2 Hadar BEN-

YOAV1,3 1 Ben gurion univeristy of the negev, Israel 2 Cincinnati Childrens Hospital Medical Center, United States 3 Corresponding author: benyoav@bgu.ac.il

Sickle cell disease is a common inherited blood disorder that leads to major morbidity and early mortality. In order to increase sickle cell treatment efficiency, it is necessary to directly measure the concentration levels of the administered drugs in serum or blood and to establish pharmacokinetics profiles to generate individualized dosing plans.(a) We are developing a low-cost and simple test for rapid quantification of the FDA approved drug hydroxyl urea in biological samples, in order to improve the way the dosing is established and the treatment is monitored.

The main challenge of in-situ analysis of unlabeled redox-active molecules in biofluids is the interference from other redox molecules generating overlapping electrochemical signals (e.g., uric acid, ascorbic acid). We modified the sensing microelectrode with 5 different materials (chitosan hydrogel, alginate hydrogel, molybdenum sulfide, tungsten sulfide, and carbon nano-dots) that allows tuning the partial selectivity of each of the electrode in the array towards hydroxyl urea while decreasing the influence of the interfering molecules.

The selective modification of 32 microelectrodes generates electrochemical interfaces with different properties allowing generating multiple electrochemical signatures corresponding to the drug hydroxyl urea. The physical properties of each electrodeposited material differ, thus generating variable specificity toward the analytes and the interfering redox molecules. The complex variability of the electrochemical signal in the presence of interfering redox active molecules is analyzed via principal component analysis. The determination of hydroxyl urea is possible in finger pricked volumes of a synthetic serum (10-20 micro-L) via the characteristic oxidation peak of hydroxyl urea observed with differential pulse voltammetry at 0.65 V vs Ag/AgCl. The selective functionalization of the 32 microelectrodes also enables the quantification of hydroxyl urea levels in biological samples of sick children with sickle cell disease. The authors thank the Ilse Katz Institute for Nanoscale Science and Technology for the help in Microfabrication and material characterization. We thank the Cincinnati children hospital and Ben Gurion University BG3C Pediatric Medical Device Initiative for funding. The authors also thank the Marcus family donation which support Dr. Cazelles via the Water Science Fund of the Ben-Gurion University of the Negev. [1] Tshilolo L, et al. Hydroxyurea for children with sickle cell anemia in sub-Saharan Africa, N Engl J Med., 2019, 380, 121-131

31

Selective charge trapping and release in nanoscale films Floriane Sturm*, Yonatan Hamo, Michal Lahav, and Milko van der Boom

The Weizmann Institute of Science, Department of Organic Chemistry, 761001 Rehovot, Israel. Email: florianesturm@online.de

We demonstrate selective charge trapping and release in nanoscale-thick layers of iron and osmium complexes. Electrochromic metallo-organic films are generated by Layer-by-layer spin-coating on transparent conductive oxides.1 These molecular assemblies consist of isostructural polypyridine complexes of bivalent ruthenium, iron and osmium which are cross-linked by coordination with palladium dichloride. We positioned these well-defined molecular layers on the electrode surface in such a manner that enable control over the charge trapping layer–identity. With ruthenium as electron-mediator directly attached to the electrode, we are exploring the photo-electrochemical properties of our films as well as redox and electrochromic behavior.2,3

References

(1) Elool Dov, N.; Shankar, S.; Cohen, D.; Bendikov, T.; Rechav, K.; Shimon, L. J. W.; Lahav, M.; van der Boom, M. E. Electrochromic Metallo-Organic Nanoscale Films: Fabrication, Color Range, and Devices. J. Am. Chem. Soc. 2017, 139, 11471–11481.

(2) Balgley, R.; Algavi, Y,; Elool Dov, N.; Lahav, M.; van der Boom, M. E. Light-Triggered Release of Trapped Charges in Molecular Assemblies Angew. Chem. Int. Ed. 2018, 57, 1-7.

(3) Malik, N.; Elool Dov, N.; de Ruiter, G.; Lahav, M.; van der Boom, M. E. On-Surface Self-Assembly of Stimuli-Response Metallo-Organic Films: Automated Ultrasonic Spray-Coating and Electrochromic Devices ACS Appl. Mater. Interfaces 2019, 11, 22858-22868.

32

DROP-ON-DEMAND 3D PRINTED LITHIUM-ION BATTERIES

Ido Ben-Barak, Dan Schneier, Yosef Kamir, Meital Goor, Inna Shekhtman, Diana Golodnitsky* and Emanuel Peled**

School of Chemistry, Faculty of Exact Sciences, Tel Aviv University Tel Aviv, Israel

* golod@tauex.tau.ac.il, ** peled@tauex.tau.ac.il

The recent trend of accelerated miniaturization of electronic devices has increased the demand for microbatteries of different geometries and chemistries, with high customizability and low manufacturing cost. Devices for applications such as personal wearable electronics, medical implants and remote sensors require small-size, but high-energy-density batteries, often with extraordinary design restriction and highly specific requirements. To facilitate the production of microbatteries of this type, we plan to use drop-on-demand dispensing, a highly robust printing method already used for various types of functional materials. This method, based on piezoelectrically actuated mechanical droplet formation, enables high accuracy and repeatability in the printing of active-material inks with different properties and rheology parameters. We have used this method to print various types of active materials for lithium-ion batteries, including cathode (lithium iron phosphate, LFP) and anode (silicon-nickel-based nanoparticles). Both yielded repeatable printability at a resolution below 200µm, which allows customization of the printing to various geometries, including 3D construction of upright electrodes. We found that the electrochemical performance of printed active materials is highly competitive with traditional manufacturing methods. Cathodes show very high specific capacity, up to 160mAh/g LFP, close to its theoretical capacity and good cycleability. Electrochemical impedance spectroscopy of cathodes shows that cathode chemistry and performance are unaffected by the printing process. Hence, direct implementation of well-established equivalent-circuit models is enabled for data analysis. Anodes also show high capacity – up to 1200mAh/g anode – and electrochemical behavior consistent with that of anodes prepared by traditional methods. We studied the adhesion of printed anodes to several current collectors and present methods of improving it, both by modification of the current collector and the anode ink itself. The anodes with improved adhesion gave longer cycle life and better performance of microbatteries printed in nonconventional geometries. As a substitute for typical battery separators, we have developed a self-pore-forming ink to be printed between electrodes. The ink is based on binders similar to those of the cathode and anode, which enable improved adhesion, high uptake of liquid electrolyte, and mechanical and electrochemical compatibility. Our results inspire further studies, development of manufacturing protocols, and designs for highly customizable batteries. Such development is of particular importance for small-scale and flexible production in many fields of applications, such as in-situ 3D printing of embedded batteries during the assembly process of electronic devices.

33

SHOULD WE POSE A CLOSURE PROBLEM FOR CAPACITIVE CHARGING OF POROUS ELECTRODES?

Amit N. Shocron, Matthew E. Suss*

Faculty of Mechanical Engineering, Technion – Israel Institute of Technology, Haifa, Israel

*e-mail: mesuss@technion.ac.il Porous conductive electrodes are often used in electrochemical systems to drive transport processes via electrochemical reactions or capacitive charging. Typical electrodes are carbon-based and upon charging develop electric double layers (EDLs) along pores. Electrodes undergoing capacitive charging, without electrochemical reactions, are used for several applications, such as supercapacitors and capacitive deionization. Such porous electrodes often possess a complex and spatially random internal pore structure. In order to model transport processes in such structures, often volume averaging is employed. Transport equations of electrochemical systems contain nonlinear electromigration terms, resulting in the need for a closure problem describing the perturbed concentration and potential. However, the closure problem has been typically neglected ad hoc in electrochemical systems, for example by assuming "slowly varying parameters" [1], where the concentration and potential perturbations are assumed to be much smaller than the volume-averaged value. To our knowledge, only the work of Gabitto and Tsouris posed and solved the closure problem for capacitively charging porous electrodes [2]. Posing and solving the closure problem results in a more accurate solution at the cost of significant mathematical complexity. We here study whether a closure problem is necessary towards accurately modeling transport processes in cells involving capacitive electrodes. To do so, we compared a 2D in-pore model to the simplified 1D volume-averaged model. Figure 1 presents concentration fields of a slit-shape pore (Figure 1a, b and c) and a comparison between the wall concentration profile to the concentration of the 1D volume-averaged model (Figure 1d, e and f). At early time (Figure 1a and d) there is strong disagreement between the 2D in-pore model and the 1D volume-averaged model. For later time (Figure 1b and e), the models still do not match; however, better agreement can be observed. At even later time (Figure 1c and f), there is a good agreement between the two models. Therefore, we conclude the two models fairly agree for long enough times, as expected from theory. We also investigated pore with wavy walls shapes. This comparison lead to conclusion that the closure problem can be simplified under couple of theoretical constraints, while tortuosity effects must be considered.

Figure 1: Predicted concentration fields for the 2D in-pore model (a, b and c), and comparison between the wall concentration profile from the 2D in-pore model to the concentration profile of the 1D volume-averaged model (d, e and f). References [1] Biesheuvel, P.M., and Bazant, M.Z., "Nonlinear dynamics of capacitive charging and desalination by porous electrodes". Pyhs. Rev. E – Stat. Nonlinear, Soft Matter Phys., 81, 1-12 (2010). [2] Gabitto, J. and Tsouris, C. "Volume averaging study of the capacitive deionization process in homogeneous porous media". Transp. Porous Media, 109, 61-80 (2015).

34

Energy Storage in Drop Cast and Electro-reduced Graphene Oxide Films

H. Avraham*1,2

, E. Korin1, A. Bettelheim

1

1Ben –Gurion University, Chemical Engineering Department, Beer Sheva, Israel

2Nuclear Research Center, POB 9001 Beer Sheva, Israel

*hananavra@gmail.com Graphene large surface area, high conductivity and chemical resistance make it one of the best candidates as hydrogen storage material and an ideal material in the fabrication of ultra-capacitors. Graphene oxide (GO), which is an oxidized version of graphene, has electronegative functional groups such as epoxy, phenol and carboxyl. These groups are hydrophilic and electrochemically active, and therefore graphene oxide oxygenation level affects its electrical conductivity, solubility in water and its higher pseudo-capacitance performance. Graphene oxide chemical composition (and oxygenation level) can be controlled electrochemically. The effects of the concentration and the type of graphene functional groups on its capacitance and electrochemical hydrogen storage properties are not clear. In the current work, we examined the capacitance and hydrogen storage capacity of drop cast and electrodeposited films obtained from GO suspensions. Both films showed a similar gradual decrease in pseudo-capacitance as a function of the reducing cathodic potentials while hydrogen storage capacitance increased up to -1.5V (vs Hg/HgO) and then decreased due to the possible damage of the films due to the higher hydrogen evolution rate. However the electrodeposited graphene oxide films showed better stability at the higher cathodic potentials. This may have an important impact on the use of graphene suspensions and coatings in electrochemical energy conversion devices.

35

IMPROVING THE PERFORMANCE OF NI-RICH NCM811 CATHODE MATERIALS FOR LI-ION BATTERIES BY DOPING WITH MOLYBDENUM

F. A. Susai1*, D. Kovacheva2, A. Chakraborty1, T. Kravchuk3, M. Talianker4, J. Grinblat1, D. T. Major1, B. Markovsky1, D. Aurbach1

1Department of Chemistry and Institute for Nanotechnology and Advanced Materials (BINA) , Bar-Ilan

University, Ramat-Gan 52900, Israel 2Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria

3Solid State Institute, Technion – Israel Institute of Technology, Haifa 32000, Israel 4Department of Materials Engineering, Ben-Gurion University of the Negev,

Beer-Sheva 84105, Israel * Corresponding author : sfamalraj@gmail.com

The development of cathode materials for Li-ion batteries (LIBs) with superior electrochemical properties – high capacity and cycling stability, low voltage fade - is key for the next generation of these power sources, especially for electric vehicles application. Ni-rich materials of layered structure LiNixCoyMnzO2, x > 0.5 are promising candidates as cathodes for advanced LIBs. The structural and cycling stability of Ni-rich cathodes can be remarkably improved by doping with small amount of extrinsic multivalent cations (Al3+, Zr4+, Ta5+, etc). Based on DFT calculations for LiNi0.8Co0.1Mn0.1O2, it was demonstrated in this work that Mo6+ cations preferably substitute Ni cations in the layered structure due to the lowest substitution energy compared to Li, Co, and Mn. We established that the electrochemical behavior of LiNi0.8Co0.1Mn0.1O2 as a positive electrode material for Li ion batteries can be substantially improved by doping with 1 – 3 mol. % of Mo6+, in terms of lowering the irreversible capacity loss during the 1st cycle, increasing discharge capacity and rate capability(as shown in Figure-1), decreasing capacity fade upon prolonged cycling, lowering the voltage hysteresis and charge-transfer resistance. The latter is attributed to the presence of additional conduction bands near the Fermi level of the Mo-doped LiNi0.8Co0.1Mn0.1O2, which facilitate Li-ions and electron transfer within the doped material. Therefore, the charge-transfer resistance of Mo-doped electrodes is lower, as shown by impedance spectroscopy. We discuss in this presentation a unique segregation phenomenon, in which the surface concentration of the transition metals and Mo-dopant differs from that in the bulk. This near surface segregation of the Mo-dopant seems to have a stabilization effect on Ni-rich (Ni=80 at. %) cathode materials.

Figure-1(a) Results of the rate capability tests and (b) cycling performance of NCM811 undoped and 1

mol.% Mo and 3 mol.% Mo-doped NCM811 electrodes obtained at 30 C at a C/3 rate.

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Bio-fuel cells based on “mini-electrosomes”

A. Boyarski1, A. A. Furman2, S. Morais2,3, E. Bayer2,3, L. Alfonta1,3

1. Department of Chemistry, Ben-Gurion University of Negev 2. Department of Biomolecular Sciences, Weizmann Institute of Science

3. Department of Life Sciences, Ben-Gurion University of Negev *e-mail: boyarska@post.bgu.ac.il

"Classic" enzymatic fuel cells are small devices that use enzymes to catalyze one specific electrochemical reaction. The main limitation of such biofuel-cells is the extremely low power outputs. Power outputs by single enzyme catalysis are restricted to a maximum amount of four electrons, depending on the enzyme used. To overcome this limitation and maximize the energy received from one molecule of fuel, it needs to go through full oxidation. Therefore, we assembled an enzymatic cascade which oxidizes methanol completely, up to carbon di-oxide. The cascade is composed of three dehydrogenase enzymes, catalyzing a sequential biochemical reaction. The cascade contains alcohol, formaldehyde and formate dehydrogenases. All three enzymes are bound to a non-catalytic scaffolding polypeptide through site-specific cohesin-dockerin interactions, which allow an efficient substrate channeling between the enzymes. To maximize the efficiency even further, the whole enzymatic complex is bound directly to an electrode through a specifically designed linker. The three enzymes expression was optimized and each one was catalytically characterized separately. Enzyme attachment to the scaffoldin was observed, however cohesin-dockerin interactions decreased the catalytic activity. Successful binding of scaffoldin to the electrode was achieved. Currently, binding of enzymes attached scaffoldin is being assembled and will be characterized on the electrode.

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